feat: 帖子编辑功能（用户限制）

- 发布后24小时内可编辑
- 最多修改5次
- 编辑按钮仅作者可见
- 显示编辑次数和剩余次数
- 数据库新增 edit_count 和 last_edit_at 字段

frontend/post.html

@@ -56,9 +56,47 @@
         <div id="repliesList" class="mt-6 space-y-4"></div>
     </main>
 
+    <!-- 编辑弹窗 -->
+    <div id="editModal" class="fixed inset-0 bg-black/50 z-50 hidden items-center justify-center p-4">
+        <div class="bg-white rounded-xl w-full max-w-2xl max-h-[90vh] overflow-hidden flex flex-col">
+            <div class="p-4 border-b flex justify-between items-center">
+                <h3 class="font-bold text-lg">编辑帖子</h3>
+                <button onclick="closeEditModal()" class="text-gray-400 hover:text-gray-600">
+                    <i class="ri-close-line text-xl"></i>
+                </button>
+            </div>
+            <div class="p-6 flex-1 overflow-auto">
+                <div id="editWarning" class="mb-4 p-3 bg-yellow-50 text-yellow-700 rounded-lg text-sm hidden"></div>
+                <div class="space-y-4">
+                    <div>
+                        <label class="block text-sm font-medium text-gray-700 mb-1">标题</label>
+                        <input type="text" id="editTitle" class="w-full px-3 py-2 border border-gray-200 rounded-lg focus:ring-2 focus:ring-blue-500">
+                    </div>
+                    <div>
+                        <label class="block text-sm font-medium text-gray-700 mb-1">内容</label>
+                        <textarea id="editContent" rows="10" class="w-full px-3 py-2 border border-gray-200 rounded-lg focus:ring-2 focus:ring-blue-500 resize-none"></textarea>
+                    </div>
+                    <div>
+                        <label class="block text-sm font-medium text-gray-700 mb-1">标签（逗号分隔）</label>
+                        <input type="text" id="editTags" class="w-full px-3 py-2 border border-gray-200 rounded-lg focus:ring-2 focus:ring-blue-500" placeholder="如: Python, 后端, API">
+                    </div>
+                </div>
+            </div>
+            <div class="p-4 border-t flex gap-3 justify-end">
+                <button onclick="closeEditModal()" class="px-4 py-2 border border-gray-300 text-gray-700 rounded-lg hover:bg-gray-50">
+                    取消
+                </button>
+                <button onclick="saveEdit()" class="px-4 py-2 gradient-bg text-white rounded-lg hover:opacity-90">
+                    保存修改
+                </button>
+            </div>
+        </div>
+    </div>
+
     <script>
         let currentUser = null;
         let currentPostId = null;
+        let currentPost = null;
         let postLiked = false;
 
         // 获取帖子ID
@@ -82,17 +120,49 @@
         }
 
         async function loadPost() {
-            const res = await fetch(`/api/posts/${currentPostId}`);
+            const res = await fetch('/api/posts/' + currentPostId);
             const post = await res.json();
             
             if (post.error) {
-                document.getElementById('postContent').innerHTML = `
-                    <div class="p-6 text-center text-gray-500">${post.error}</div>
-                `;
+                document.getElementById('postContent').innerHTML = '<div class="p-6 text-center text-gray-500">' + post.error + '</div>';
                 return;
             }
+            
+            currentPost = post;
+            document.title = post.title + ' - 技术论坛';
+
+            // 检查是否可编辑
+            let canEdit = false;
+            let editInfo = '';
+            if (currentUser && post.author.id === currentUser.id) {
+                const createdTime = new Date(post.created_at);
+                const now = new Date();
+                const hoursPassed = (now - createdTime) / (1000 * 60 * 60);
+                const editCount = post.edit_count || 0;
+                
+                if (hoursPassed > 24) {
+                    editInfo = '发布超过24小时，无法编辑';
+                } else if (editCount >= 5) {
+                    editInfo = '已达到最大修改次数（5次）';
+                } else {
+                    canEdit = true;
+                    editInfo = '剩余修改次数: ' + (5 - editCount) + ' 次，时限: ' + Math.ceil(24 - hoursPassed) + ' 小时';
+                }
+            }
 
             // 渲染帖子
+            let editBtnHtml = '';
+            if (canEdit) {
+                editBtnHtml = '<button onclick="openEditModal()" class="px-4 py-2 border border-gray-300 rounded-lg hover:bg-gray-50 flex items-center gap-1"><i class="ri-edit-line"></i> 编辑</button>';
+            } else if (currentUser && post.author.id === currentUser.id && editInfo) {
+                editBtnHtml = '<span class="text-sm text-gray-400">' + editInfo + '</span>';
+            }
+
+            let editCountHtml = '';
+            if (post.edit_count > 0) {
+                editCountHtml = '<span class="text-xs text-gray-400 ml-2">已编辑 ' + post.edit_count + ' 次' + (post.last_edit_at ? '，最后编辑: ' + new Date(post.last_edit_at).toLocaleString() : '') + '</span>';
+            }
+
             document.getElementById('postContent').innerHTML = `
                 <div class="p-6">
                     <!-- 类型标签 -->
@@ -100,6 +170,7 @@
                         <span class="px-2 py-1 rounded text-xs ${post.type === 'discussion' ? 'bg-blue-100 text-blue-600' : 'bg-purple-100 text-purple-600'}">
                             ${post.type === 'discussion' ? '技术交流' : '工具分享'}
                         </span>
+                        ${editCountHtml}
                     </div>
                     
                     <!-- 标题 -->
@@ -118,11 +189,9 @@
                     <div class="prose text-gray-700 leading-relaxed mb-6 whitespace-pre-wrap">${post.content}</div>
                     
                     <!-- 标签 -->
-                    ${post.tags.length > 0 ? `
+                    ${post.tags && post.tags.length > 0 ? `
                         <div class="flex flex-wrap gap-2 mb-6">
-                            ${post.tags.map(tag => `
-                                <span class="px-3 py-1 bg-gray-100 text-gray-600 rounded-full text-sm">${tag}</span>
-                            `).join('')}
+                            ${post.tags.map(tag => '<span class="px-3 py-1 bg-gray-100 text-gray-600 rounded-full text-sm">' + tag + '</span>').join('')}
                         </div>
                     ` : ''}
                     
@@ -132,7 +201,8 @@
                             <span><i class="ri-eye-line mr-1"></i> ${post.views} 浏览</span>
                             <span id="likesCount"><i class="ri-heart-line mr-1"></i> ${post.likes} 赞</span>
                         </div>
-                        <div class="flex gap-3">
+                        <div class="flex gap-3 items-center">
+                            ${editBtnHtml}
                             <button onclick="likePost()" id="likeBtn" class="px-4 py-2 border border-gray-300 rounded-lg hover:bg-gray-50 flex items-center gap-1">
                                 <i class="ri-heart-line"></i> 赞
                             </button>
@@ -170,7 +240,7 @@
                                 <button onclick="likeReply('${reply.id}')" class="hover:text-blue-500">
                                     <i class="ri-heart-line"></i> ${reply.likes}
                                 </button>
-                                <button onclick="replyTo('${reply.id}')" class="hover:text-blue-500">
+                                <button onclick="replyTo('${reply.author.username}')" class="hover:text-blue-500">
                                     <i class="ri-reply-line"></i> 回复
                                 </button>
                             </div>
@@ -180,6 +250,68 @@
             `).join('');
         }
 
+        function openEditModal() {
+            document.getElementById('editTitle').value = currentPost.title;
+            document.getElementById('editContent').value = currentPost.content;
+            document.getElementById('editTags').value = currentPost.tags ? currentPost.tags.join(', ') : '';
+            
+            // 显示编辑限制提示
+            const createdTime = new Date(currentPost.created_at);
+            const now = new Date();
+            const hoursPassed = (now - createdTime) / (1000 * 60 * 60);
+            const editCount = currentPost.edit_count || 0;
+            
+            document.getElementById('editWarning').innerHTML = '剩余修改次数: ' + (5 - editCount) + ' 次，时限: ' + Math.ceil(24 - hoursPassed) + ' 小时';
+            document.getElementById('editWarning').classList.remove('hidden');
+            
+            document.getElementById('editModal').classList.remove('hidden');
+            document.getElementById('editModal').classList.add('flex');
+        }
+
+        function closeEditModal() {
+            document.getElementById('editModal').classList.add('hidden');
+            document.getElementById('editModal').classList.remove('flex');
+        }
+
+        async function saveEdit() {
+            const title = document.getElementById('editTitle').value.trim();
+            const content = document.getElementById('editContent').value.trim();
+            const tagsStr = document.getElementById('editTags').value.trim();
+            const tags = tagsStr ? tagsStr.split(',').map(t => t.trim()).filter(t => t) : [];
+            
+            if (!title || title.length < 5) {
+                alert('标题至少5个字符');
+                return;
+            }
+            if (!content || content.length < 10) {
+                alert('内容至少10个字符');
+                return;
+            }
+            
+            try {
+                const res = await fetch('/api/posts/' + currentPostId + '/edit', {
+                    method: 'POST',
+                    headers: {
+                        'Authorization': 'Bearer ' + localStorage.getItem('token'),
+                        'Content-Type': 'application/json'
+                    },
+                    body: JSON.stringify({ title, content, tags })
+                });
+                
+                const data = await res.json();
+                
+                if (data.success) {
+                    closeEditModal();
+                    loadPost();
+                    alert('编辑成功！');
+                } else {
+                    alert(data.error || '编辑失败');
+                }
+            } catch (err) {
+                alert('网络错误');
+            }
+        }
+
         async function submitReply() {
             if (!currentUser) {
                 alert('请先登录');
@@ -193,10 +325,10 @@
             }
 
             try {
-                const res = await fetch(`/api/posts/${currentPostId}/reply`, {
+                const res = await fetch('/api/posts/' + currentPostId + '/reply', {
                     method: 'POST',
                     headers: {
-                        'Authorization': `Bearer ${localStorage.getItem('token')}`,
+                        'Authorization': 'Bearer ' + localStorage.getItem('token'),
                         'Content-Type': 'application/json'
                     },
                     body: JSON.stringify({ content })
@@ -221,10 +353,10 @@
             }
 
             try {
-                const res = await fetch(`/api/posts/${currentPostId}/like`, {
+                const res = await fetch('/api/posts/' + currentPostId + '/like', {
                     method: 'POST',
                     headers: {
-                        'Authorization': `Bearer ${localStorage.getItem('token')}`
+                        'Authorization': 'Bearer ' + localStorage.getItem('token')
                     }
                 });
                 const data = await res.json();
@@ -241,7 +373,7 @@
                         btn.classList.remove('border-red-300', 'text-red-500');
                     }
                     
-                    countEl.innerHTML = `<i class="ri-heart-line mr-1"></i> ${data.likes_count} 赞`;
+                    countEl.innerHTML = '<i class="ri-heart-line mr-1"></i> ' + data.likes_count + ' 赞';
                 }
             } catch (err) {
                 console.error(err);
@@ -255,13 +387,12 @@
             });
         }
 
-        function replyTo(replyId) {
+        function replyTo(username) {
+            document.getElementById('replyContent').value = '@' + username + ' ';
             document.getElementById('replyContent').focus();
-            document.getElementById('replyContent').placeholder = '回复中...';
         }
 
         function likeReply(replyId) {
-            // TODO: 实现回复点赞
             alert('功能开发中');
         }
     </script>