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.

bot/main.py

@@ -6,7 +6,7 @@ from aiogram.client.default import DefaultBotProperties
 from aiogram.client.session.aiohttp import AiohttpSession
 from remnawave import RemnawaveSDK
 
-from bot.handlers import routers
+from bot.handlers import admin_routers, client_routers, system_routers
 from bot.middlewares import DIMiddleware
 from config import settings
 from db.session import async_session
@@ -55,8 +55,12 @@ async def main():
     default = DefaultBotProperties(parse_mode="HTML")
     bot = Bot(token=settings.bot_token, default=default, session=aiohttp_session)
 
-    for router in routers:
-        dp.include_router(router)
+    for r in admin_routers:
+        dp.include_router(r)
+    for r in client_routers:
+        dp.include_router(r)
+    for r in system_routers:
+        dp.include_router(r)
 
     await dp.start_polling(bot)