fix: 版本检查 — 后端设置 checked 字段 + 前端 info 合并显示

- UpdateService.status 增加 checked/current_version/latest_version
- _check_version 成功后设置 checked=True
- 设置页 update-notes 合并版本信息和时间戳 (替代 innerHTML 覆盖)

Co-Authored-By: Claude <noreply@anthropic.com>

services/update_service.py

@@ -77,7 +77,8 @@ class UpdateService:
         self._task: Optional[asyncio.Task] = None
         self._running = False
         self.status: dict = {"state": "idle", "progress": 0, "error": "",
-                             "last_check": 0, "update_available": False}
+                             "last_check": 0, "checked": False, "update_available": False,
+                             "current_version": "", "latest_version": ""}
         # 从配置读取分支和仓库地址
         try:
             init = self.sm.get_service("init")
@@ -109,6 +110,7 @@ class UpdateService:
             loop = asyncio.get_event_loop()
             data = await loop.run_in_executor(None, self._sync_fetch_json, self.version_url)
             self.status["last_check"] = time.time()
+            self.status["checked"] = True
             if not data:
                 return
             remote_fw = data.get("framework", {})