LOOPIN-022B — Implement basic report system API

[shaig-mahmudov]

• Type: Backend
• Priority: Optional
• Branch: feature/LOOPIN-022B-report-system-api
• Description: Build endpoints for logging and updating user reports regarding groups or messages.
• Acceptance Criteria:
  • Logged-in users can submit reports.
  • Reports are saved with PENDING status, visible only to admins.