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>

db.mjs

@@ -771,6 +771,53 @@ export async function migrateSchema(pool) {
     )
   `);
 
+  if (!(await columnExists(pool, 'h5_page_records', 'workspace_relative_path'))) {
+    await pool.query(
+      `ALTER TABLE h5_page_records
+       ADD COLUMN workspace_relative_path VARCHAR(512) NULL AFTER draft_content_ref`,
+    );
+  }
+  if (!(await indexExists(pool, 'h5_page_records', 'idx_h5_pages_workspace_path'))) {
+    await pool.query(
+      `ALTER TABLE h5_page_records
+       ADD KEY idx_h5_pages_workspace_path (user_id, workspace_relative_path, updated_at)`,
+    );
+  }
+  if (!(await columnExists(pool, 'h5_assets', 'workspace_relative_path'))) {
+    await pool.query(
+      `ALTER TABLE h5_assets
+       ADD COLUMN workspace_relative_path VARCHAR(512) NULL AFTER display_name`,
+    );
+  }
+  if (!(await indexExists(pool, 'h5_assets', 'idx_h5_assets_workspace_path'))) {
+    await pool.query(
+      `ALTER TABLE h5_assets
+       ADD KEY idx_h5_assets_workspace_path (user_id, workspace_relative_path, updated_at)`,
+    );
+  }
+  await pool.query(
+    `UPDATE h5_page_records p
+     JOIN h5_page_versions pv ON pv.id = p.current_version_id
+     SET p.workspace_relative_path = JSON_UNQUOTE(JSON_EXTRACT(pv.source_snapshot_json, '$.relative_path'))
+     WHERE p.workspace_relative_path IS NULL
+       AND JSON_EXTRACT(pv.source_snapshot_json, '$.relative_path') IS NOT NULL
+       AND JSON_UNQUOTE(JSON_EXTRACT(pv.source_snapshot_json, '$.relative_path')) <> ''`,
+  );
+  await pool.query(
+    `UPDATE h5_assets a
+     JOIN h5_space_categories c ON c.id = a.category_id AND c.user_id = a.user_id
+     SET a.workspace_relative_path = CASE
+       WHEN a.original_filename LIKE 'public/%' OR a.original_filename LIKE 'oa/%'
+         THEN a.original_filename
+       WHEN c.category_code IN ('public', 'oa')
+         THEN CONCAT(c.category_code, '/', a.original_filename)
+       ELSE NULL
+     END
+     WHERE a.workspace_relative_path IS NULL
+       AND a.status <> 'deleted'
+       AND c.category_code IN ('public', 'oa')`,
+  );
+
   await pool.query(`
     CREATE TABLE IF NOT EXISTS h5_user_feedback (
       id CHAR(36) PRIMARY KEY,