feat(server): 添加系统重启功能支持

添加后台任务支持用于处理系统重启请求，实现延迟进程终止机制，
允许系统安全地重启并在重启后自动恢复服务。

feat(frontend): 实现前端系统重启控制面板

在状态页面添加重启对话框组件，提供用户友好的重启确认界面，
包含重启状态监控和错误处理功能，确保用户可以安全重启系统。

docs(deployment): 更新部署指南添加URL协议要求说明

详细说明NANO_AUTHZ_URL和NANO_DEPLOY_URL环境变量必须包含
http://协议前缀的要求，添加常见错误示例和容器重建步骤，
帮助用户避免注册页面502错误问题。

app-instance/backend/nanobot/web/server.py

@@ -18,6 +18,7 @@ from urllib.parse import urlsplit, urlunsplit
 
 import httpx
 from fastapi import (
+    BackgroundTasks,
     FastAPI,
     File,
     Form,
@@ -112,6 +113,13 @@ async def _reconcile_managed_outlook_mcp(config: Config) -> bool:
     return before != after
 
 
+def _terminate_process_after_delay(delay_seconds: float = 1.0, exit_code: int = 1) -> None:
+    if delay_seconds > 0:
+        time.sleep(delay_seconds)
+    logger.warning("Self-restart requested; exiting backend process with code {}", exit_code)
+    os._exit(exit_code)
+
+
 # ============================================================================
 # Request/Response models
 # ============================================================================
@@ -1534,6 +1542,20 @@ def _register_routes(app: FastAPI) -> None:
                 app.state.auth_tokens.pop(token, None)
         return {"ok": True}
 
+    @app.post("/api/system/restart", status_code=202)
+    async def restart_system(
+        background_tasks: BackgroundTasks,
+        authorization: str | None = Header(default=None),
+    ):
+        username = _require_web_user(app, authorization)
+        logger.warning("Restart requested by user {}", username)
+        background_tasks.add_task(_terminate_process_after_delay, 1.0, 1)
+        return {
+            "ok": True,
+            "restarting": True,
+            "detail": "Restart scheduled",
+        }
+
     # ------ Chat ------
 
     @app.post("/api/chat")