feat: POST /admin/demo-seed — admin can trigger demo data seeding and see the raw error

sync-server/src/index.mjs

@@ -77,7 +77,7 @@ const server = http.createServer(async (req, res) => {
     }
 
     // ---- 管理（仅 is_admin 登录会话） ----
-    if (route === '/admin/users' || route === '/admin/invites' || route.startsWith('/admin/invites/')) {
+    if (route === '/admin/users' || route === '/admin/invites' || route === '/admin/demo-seed' || route.startsWith('/admin/invites/')) {
       let auth;
       try { auth = authUser(req); }
       catch (e) { return send(e.code || 401, false, e.message); }
@@ -156,6 +156,16 @@ const server = http.createServer(async (req, res) => {
         if (!r.changes) return send(404, false, '邀请码不存在');
         return send(200, true, { deleted: r.changes });
       }
+      if (req.method === 'POST' && route === '/admin/demo-seed') {
+        const demoRow = db.prepare('SELECT id FROM users WHERE username=?').get('demo');
+        if (!demoRow) return send(404, false, 'demo 账号不存在');
+        try {
+          const r = commandsFor(demoRow.id).handleCommand('demo_seed', {});
+          return send(200, true, r);
+        } catch (e) {
+          return send(500, false, 'demo_seed 失败: ' + (e.message || String(e)));
+        }
+      }
       return send(404, false, 'not found');
     }