Overview

This PR enhances the authentication module with two key requirements:

1. Gmail Registration Restriction: Enforces that all newly registered accounts must use a @gmail.com email address.
2. Avatar File Upload Pipeline: Transitions avatar updates from manual URL inputs to direct image file uploads (multipart/form-data), backed by the abstract storage layer (IStorageService).

Key Changes

1. Gmail Domain Enforcement

• Updated registerSchema with validation ensuring email addresses end with @gmail.com (case-insensitive).
• Added unit tests covering standard Gmail addresses, sub-addressing (+tag), and rejection of non-Gmail domains.

2. Avatar Upload Middleware

• Integrated multer with memory storage.
• Added uploadAvatarMiddleware enforcing a 5MB maximum file size and strict image MIME type validation (image/jpeg, image/png, image/webp, image/gif), throwing standardized AppError (422 VALIDATION_ERROR).

3. Service & Storage Integration

• AuthService.uploadAvatar:
  • Streams image buffers directly to IStorageService under avatars/<userId>-<timestamp>.<ext>.
  • Automatically cleans up obsolete avatar files from storage when a new avatar is uploaded.
  • Updates the user record in PostgreSQL and returns the updated user profile.
• AuthService.getAvatarStream:
  • Validates and securely reads stored avatar files with MIME detection for HTTP streaming.
• Profile Update Decoupling:
  • Removed avatarUrl from UpdateMeDto and updateMeSchema. The PATCH /api/v1/auth/me endpoint now strictly handles profile fields (fullName).

4. Endpoints & Audit Logging

• POST /api/v1/auth/avatar: Authenticated multipart upload endpoint.
• GET /api/v1/auth/avatar/:fileName: Public endpoint serving uploaded avatars.
• Added UPDATE_AVATAR action to AUDIT_ACTIONS.