Refactor bot handlers and keyboards; implement admin features

- Removed unused prehandling, referrals, support, and states files.
- Updated admin and client handlers to improve structure and functionality.
- Introduced admin filters and routers for better access control.
- Added new billing and deposit functionalities for client interactions.
- Enhanced keyboard layouts for admin and client menus.
- Implemented promotion handling for admin users.
- Updated configuration to include admin settings.
- Improved utility functions for quote fetching and menu text building.
- Added common handlers for undefined commands and message deletions.

repositories/users.py

@@ -2,6 +2,7 @@ import datetime
 
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.sql.functions import count
 
 from db.models import User
 from db.models.transactions import BalanceTransaction, BalanceTxType
@@ -121,3 +122,9 @@ class UserRepository:
 
         await session.commit()
         return user
+
+    async def user_count(self, session: AsyncSession) -> int:
+        stmt = select(count()).select_from(User)
+        res = await session.execute(stmt)
+
+        return int(res.scalar_one_or_none())