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/handlers/client/support.py

@@ -0,0 +1,27 @@
+import logging
+
+from aiogram import F, Router
+from aiogram.filters import Command
+from aiogram.fsm.context import FSMContext
+from aiogram.types import CallbackQuery, Message
+
+from bot.keyboards.client import support_url_kb
+from bot.texts import SUPPORT_INIT
+
+router = Router()
+logger = logging.getLogger(__name__)
+
+
+@router.callback_query(F.data == "support")
+async def support_init(cb: CallbackQuery, state: FSMContext):
+    await state.clear()
+
+    await cb.message.edit_text(text=SUPPORT_INIT, reply_markup=support_url_kb)
+
+
+@router.message(Command("support"))
+async def support_init_cmd(msg: Message, state: FSMContext):
+    await state.clear()
+    await msg.delete()
+
+    await msg.answer(text=SUPPORT_INIT, reply_markup=support_url_kb)