feat: 添加上传按钮支持图片和文件上传

www/style.css

@@ -500,6 +500,41 @@ body {
 .message-content h2 { font-size: 1.2em; }
 .message-content h3 { font-size: 1.1em; }
 
+/* 图片消息样式 */
+.message-image {
+  margin-bottom: 8px;
+}
+
+.message-image img {
+  max-width: 100%;
+  max-height: 300px;
+  border-radius: 12px;
+  cursor: pointer;
+  transition: transform 0.2s;
+}
+
+.message-image img:hover {
+  transform: scale(1.02);
+}
+
+/* 图片预览遮罩 */
+.image-preview-overlay {
+  position: fixed;
+  inset: 0;
+  background: rgba(0,0,0,0.9);
+  z-index: 1000;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: pointer;
+}
+
+.image-preview-overlay img {
+  max-width: 90%;
+  max-height: 90%;
+  border-radius: 8px;
+}
+
 .message-content ul, .message-content ol {
   margin: 8px 0;
   padding-left: 20px;
@@ -558,6 +593,85 @@ body {
   bottom: 0;
 }
 
+/* 上传按钮 */
+.attach-btn {
+  width: 44px;
+  height: 44px;
+  border-radius: 50%;
+  background: white;
+  border: 2px solid var(--border-color);
+  color: var(--text-light);
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  transition: all 0.2s;
+  flex-shrink: 0;
+}
+
+.attach-btn:hover {
+  border-color: var(--primary);
+  color: var(--primary);
+  background: rgba(102, 126, 234, 0.05);
+}
+
+.attach-btn:active {
+  transform: scale(0.95);
+}
+
+/* 上传选项面板 */
+.attach-panel {
+  position: fixed;
+  bottom: 70px;
+  left: 16px;
+  background: white;
+  border-radius: 12px;
+  box-shadow: 0 4px 20px rgba(0,0,0,0.15);
+  padding: 16px;
+  display: none;
+  z-index: 200;
+}
+
+.attach-panel.show {
+  display: block;
+  animation: slideUp 0.2s ease;
+}
+
+@keyframes slideUp {
+  from { opacity: 0; transform: translateY(10px); }
+  to { opacity: 1; transform: translateY(0); }
+}
+
+.attach-panel-content {
+  display: flex;
+  gap: 16px;
+}
+
+.attach-item {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 8px;
+  padding: 12px 16px;
+  background: rgba(102, 126, 234, 0.05);
+  border-radius: 12px;
+  cursor: pointer;
+  transition: all 0.2s;
+}
+
+.attach-item:hover {
+  background: rgba(102, 126, 234, 0.15);
+}
+
+.attach-icon {
+  font-size: 28px;
+}
+
+.attach-label {
+  font-size: 12px;
+  color: var(--text-color);
+}
+
 #userInput {
   flex: 1;
   padding: 12px 16px;