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/keyboards/admins.py

@@ -1,16 +1,16 @@
 from aiogram.types import InlineKeyboardButton, InlineKeyboardMarkup
 from aiogram.utils.keyboard import InlineKeyboardBuilder
 
-promotion_confirmation: InlineKeyboardMarkup = InlineKeyboardBuilder(
+main_menu: InlineKeyboardMarkup = InlineKeyboardBuilder(
+    [
+        [InlineKeyboardButton(text="📢 Рассылка", callback_data="promotion")],
+        [InlineKeyboardButton(text="👤 Управление пользователем", callback_data="usermgmt")],
+    ]
+).as_markup()
+
+action_confirmation: InlineKeyboardMarkup = InlineKeyboardBuilder(
     [
         [InlineKeyboardButton(text="✅", callback_data="approve")],
         [InlineKeyboardButton(text="❌", callback_data="decline")],
     ]
 ).as_markup()
-
-ticket_actions: InlineKeyboardMarkup = InlineKeyboardBuilder(
-    [
-        [InlineKeyboardButton(text="🔒", callback_data="close")],
-        [InlineKeyboardButton(text="💸 Пополнить баланс реферала", callback_data="refpay")],
-    ]
-).as_markup()