feat(mindspace): 公开页分享组件、workspace 路径与 Plaza 发布增强

- 新增 public share widget 与 workspace relative path 解析
- 增强 publications/chat-plaza 发布链路与缩略图 demo
- 补充 schema、cover 检查脚本与回归测试

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

src/components/ChatPlazaPublishModal.tsx

@@ -1,10 +1,11 @@
-import { useEffect, useRef, useState } from 'react';
+import { useCallback, useEffect, useRef, useState } from 'react';
 import { createPortal } from 'react-dom';
 import { ApiError, quickPlazaFromChat } from '../api/client';
 import { resolvePlazaPostUrl } from '../utils/publicUrl';
 import { ChatLoadingSpinner } from './ChatLoadingSpinner';
 
 type PlazaPublishPhase =
+  | { kind: 'confirm' }
   | { kind: 'loading' }
   | { kind: 'success'; plazaUrl: string }
   | { kind: 'already'; plazaUrl: string; message: string }
@@ -28,11 +29,15 @@ export function ChatPlazaPublishModal({
   messageId: string;
   onClose: () => void;
 }) {
-  const [phase, setPhase] = useState<PlazaPublishPhase>({ kind: 'loading' });
+  const [phase, setPhase] = useState<PlazaPublishPhase>({ kind: 'confirm' });
   const closeTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
   const onCloseRef = useRef(onClose);
   onCloseRef.current = onClose;
 
+  const startPublish = useCallback(() => {
+    setPhase({ kind: 'loading' });
+  }, []);
+
   useEffect(() => {
     const prev = document.body.style.overflow;
     document.body.style.overflow = 'hidden';
@@ -52,6 +57,7 @@ export function ChatPlazaPublishModal({
   }, [onClose, phase.kind]);
 
   useEffect(() => {
+    if (phase.kind !== 'loading') return;
     const controller = new AbortController();
 
     void quickPlazaFromChat({ sessionId, messageId }, controller.signal)
@@ -79,7 +85,7 @@ export function ChatPlazaPublishModal({
       });
 
     return () => controller.abort();
-  }, [sessionId, messageId]);
+  }, [phase.kind, sessionId, messageId]);
 
   const canClose = phase.kind !== 'loading';
 
@@ -97,6 +103,21 @@ export function ChatPlazaPublishModal({
         aria-busy={phase.kind === 'loading'}
         onClick={(event) => event.stopPropagation()}
       >
+        {phase.kind === 'confirm' && (
+          <div className="chat-plaza-publish-body">
+            <h3 id="chat-plaza-publish-title">发布到 Plaza</h3>
+            <p>将把当前对话内容保存为公开页面并推送到发现广场，确认继续？</p>
+            <div className="chat-plaza-publish-actions">
+              <button type="button" className="chat-plaza-publish-close-btn" onClick={onClose}>
+                取消
+              </button>
+              <button type="button" className="chat-plaza-publish-confirm-btn" onClick={startPublish}>
+                确认发布
+              </button>
+            </div>
+          </div>
+        )}
+
         {phase.kind === 'loading' && (
           <div className="chat-plaza-publish-body">
             <ChatLoadingSpinner className="chat-plaza-publish-spinner" />