feat: implement billing system with Pally integration

- Added billing models and repository for handling bills.
- Introduced BillingService to manage payment initiation and bill creation.
- Updated user service to remove ticket-related functionality.
- Refactored settings to include new billing-related fields.
- Removed ticket-related handlers and schemas.
- Added new billing handlers for processing payments.
- Updated database schema with new bills table and status enum.
- Enhanced utility functions to calculate prices considering discounts.
- Introduced prehandling for non-private messages.
- Updated main application to initialize new billing services and repositories.

keyboards/client.py

@@ -29,6 +29,7 @@ return_to_menu: InlineKeyboardMarkup = InlineKeyboardBuilder([[_return_to_menu_b
 
 payment_gateways: InlineKeyboardMarkup = InlineKeyboardBuilder(
     [
+        [InlineKeyboardButton(text="💸 Pally (СБП / Карта)", callback_data="billing:pally")],
         [InlineKeyboardButton(text="✍️ Перейти в поддержку", url="https://t.me/maleniasupportbot")],
         [_return_to_menu_btn],
     ]
@@ -113,3 +114,12 @@ def referals_kb(share_link: str) -> InlineKeyboardMarkup:
             [_return_to_menu_btn],
         ]
     ).as_markup()
+
+
+def pay_url(url: str) -> InlineKeyboardMarkup:
+    return InlineKeyboardBuilder(
+        [
+            [InlineKeyboardButton(text="💸 Оплатить", url=url)],
+            [InlineKeyboardButton(text="❌", callback_data="menu:main")],
+        ]
+    ).as_markup()