feat: 新建对话按钮移到历史列表页顶部右侧

www/app.js

@@ -68,14 +68,12 @@ function showConversationList() {
           <span class="logo">🤖</span>
           <h1>AI助手</h1>
         </div>
+        <button class="new-chat-btn-header" id="newChatBtn" title="新建对话">
+          <svg viewBox="0 0 24 24" width="20" height="20"><path fill="currentColor" d="M19 13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/></svg>
+        </button>
       </header>
       
       <div class="list-content">
-        <button class="new-chat-btn" id="newChatBtn">
-          <svg viewBox="0 0 24 24" width="20" height="20"><path fill="currentColor" d="M19 13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/></svg>
-          新建对话
-        </button>
-        
         <div class="conversation-list" id="conversationList">
           ${conversations.length === 0 
             ? '<div class="empty-list">暂无对话记录</div>'

www/style.css

@@ -72,6 +72,30 @@ body {
   overflow-y: auto;
 }
 
+/* Header 中的新建对话按钮 */
+.new-chat-btn-header {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 40px;
+  height: 40px;
+  background: rgba(255,255,255,0.2);
+  border: none;
+  border-radius: 10px;
+  color: white;
+  cursor: pointer;
+  transition: all 0.2s;
+}
+
+.new-chat-btn-header:hover {
+  background: rgba(255,255,255,0.3);
+}
+
+.new-chat-btn-header:active {
+  transform: scale(0.95);
+}
+
+/* 原样式保留（备用） */
 .new-chat-btn {
   display: flex;
   align-items: center;