Authentication API Endpoints

[onelrian]

• Priority: HIGH | Effort: LARGE | Dependencies: TICKET-004
• Acceptance Criteria:
  • POST /auth/login - User authentication
  • POST /auth/logout - Token revocation
  • POST /auth/refresh - Token refresh
  • POST /auth/register - User registration (admin only)
  • POST /auth/forgot-password - Password reset
  • POST /auth/reset-password - Password reset confirmation
  • Rate limiting on auth endpoints
  • Audit logging for auth events
• Files: backend/src/auth/handlers.rs, backend/src/api/routes.rs