feat: first-time setup flow — no .env required for deployment

- Add GET /auth/status endpoint (returns needsSetup when no admin exists)
- Add POST /auth/setup endpoint (public first-admin registration)
- Add IsAdminExists + SetupInitialAdmin methods to AuthService
- Frontend: detect needsSetup on load, show setup page with admin registration
- Frontend: fall back to login page when setup is already complete
- Docker compose: env_file already optional (required: false), no changes needed
- Bootstrap: auto-detect BOOTSTRAP_CLUSTERS without separate enable flag

frontend/src/api/index.ts

@@ -219,6 +219,10 @@ export type NodeMetricsResponse = GeneratedNodeMetricsResponse;
 export const login = postAuthLogin;
 export const register = postAuthRegister;
 export const refreshAuth = postAuthRefresh;
+export const fetchAuthStatus = () =>
+  AXIOS_INSTANCE.get<{ needsSetup: boolean; hasUsers: boolean }>("/auth/status").then((r) => r.data);
+export const setupInitialAdmin = (data: { username: string; password: string; email?: string }) =>
+  AXIOS_INSTANCE.post<{ accessToken: string; refreshToken: string }>("/auth/setup", data).then((r) => r.data);
 export const listUsers = () => customAxiosInstance<UserResponse[]>({ url: "/users", method: "GET" });
 export const createUser = (data: AdminCreateUserRequest) =>
   customAxiosInstance<UserResponse>({ url: "/users", method: "POST", data });