2.1.0: Add version to package.json and fix formatting

Added the first BirdX Admin Panel at /admin.
Added admin/user roles with database migration support.
Added secure session-based /api/admin/* endpoints.
Added admin dashboard metrics for users, chats, messages, files, sessions, and storage usage.
Added user management for role changes, bans, password resets, and deletion.
Added chat management with search, type filtering, and deletion.
Added uploaded file management with owner, size, type, and deletion controls.
Added admin audit logs for sensitive actions.
Added ADMIN_USERNAMES bootstrap support in .env.example.
Added an Admin Panel entry in settings for admin users.