MERN Stack: Axios/Fetch Interceptor with Silent JWT Token Refresh Queue

### Problem Overview In production MERN stack web apps, access tokens expire every 10-15 minutes. When multiple components render simultaneously on a page, all 3 make concurrent HTTP requests with the expired token, resulting in simultaneous 401 Unauthorized errors. You must build an HTTP Interceptor with an Asynchronous Request Queue that intercepts 401s, initiates a single refresh call, queues all concurrent requests, and replays them automatically with the new token. ### Functional Requirements 1. **`fetch(url: string, headers?: Record<string, string>): Promise<{ status: number; data: any }>`**: - Attaches `Authorization: Bearer <token>` header to requests. - If the request returns `401`, intercepts the response. 2. **Atomic Token Refresh Locking**: - Only ONE refresh token request must be in flight at any given moment. - Other requests encountering 401s while a refresh is in progress must be enqueued into an asynchronous pending resolver queue. 3. **Queue Replay on Refresh Success**: - Once refreshed, updates the token and replays all pending queued requests. 4. **Queue Rejection on Refresh Failure**: - If token refresh fails, rejects all queued requests and calls `onSessionExpired`.