Fix OA workspace cover thumbnails and add space chat new session.

Resolve mindspace-cover images from workspace directories when generating feed thumbnails, refresh stale SVGs missing embedded photos, and disable thumbnail API caching so fixes take effect immediately. Also add a new session control to the space chat panel, including on mobile.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/components/SpaceChatPanel.tsx

@@ -48,6 +48,16 @@ export function SpaceChatPanel({
     openRecharge,
     retryConnect,
   } = chat;
+  const busy = chatState === 'streaming' || chatState === 'loading' || chatState === 'connecting';
+  const memoryLoading = chatBridge ? false : mainChat.memoryLoading;
+
+  const handleNewSession = () => {
+    if (chatBridge) {
+      void chatBridge.newSession();
+      return;
+    }
+    void mainChat.newSession();
+  };
 
   useEffect(() => {
     if (!open) return;
@@ -75,6 +85,14 @@ export function SpaceChatPanel({
           </div>
         </div>
         <div className="space-chat-panel-actions">
+          <button
+            type="button"
+            className="ghost-btn space-chat-panel-new-session"
+            disabled={busy || memoryLoading}
+            onClick={handleNewSession}
+          >
+            新会话
+          </button>
           {!hideOpenFullChat ? (
             <button type="button" className="ghost-btn" onClick={onOpenFullChat}>
               打开完整聊天