backend: add request logging middleware for endpoints

[ShantKhatri]

Summary

Add a lightweight request logger to the backend pipeline to capture method + path.

Tasks

• in apps/backend/src/app.ts, add app.addHook('onRequest', (request, reply) => ...) that logs request.method and request.url.
• confirm existing logs continue to work with pino output.
• add tests in apps/backend/src/__tests__/app.test.ts to assert hook runs by spying on app.log.info.

Acceptance Criteria

• log entry is added for each incoming request and no behavior break in existing tests.