feat: Implement payment notification system and API structure

- Added notifications for successful payments in `api/core/notifications.py`.
- Created main API entry point in `api/main.py` with FastAPI integration.
- Established routing structure in `api/routes/__init__.py` and `api/routes/pally.py` for handling payment callbacks.
- Developed billing handlers in `bot/handlers/billing.py` and `bot/handlers/buy.py` for subscription management.
- Introduced state management for user interactions in `bot/states/`.
- Created user interface elements in `bot/keyboards/` for navigation and payment processing.
- Set up middleware for dependency injection in `bot/middlewares/di.py`.
- Added support for user commands and interactions in `bot/handlers/common.py` and `bot/handlers/support.py`.
- Implemented logging and error handling throughout the bot's functionality.
- Created entry point script for API server in `entrypoints/api.sh`.

api/main.py

@@ -0,0 +1,52 @@
+from collections.abc import AsyncGenerator
+from contextlib import asynccontextmanager
+
+from aiogram import Bot
+from fastapi import FastAPI
+
+from api.routes import routers
+from config import settings
+from repositories.bills import BillsRepository
+from repositories.users import UserRepository
+from schemas.di import APIDependenciesDTO
+from services.billing_service import BillingService
+from services.user_service import UserService
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI) -> AsyncGenerator:
+    # Bot Init
+    bot = Bot(token=settings.bot_token)
+    app.state.bot = bot
+
+    user_repository = UserRepository()
+    user_service = UserService(user_repository)
+
+    bills_repository = BillsRepository()
+    bills_service = BillingService(
+        user_repository=user_repository, bills_repository=bills_repository
+    )
+
+    deps_dto = APIDependenciesDTO(
+        user_repository=user_repository,
+        user_service=user_service,
+        bills_repository=bills_repository,
+        billing_service=bills_service,
+    )
+    app.state.deps = deps_dto
+
+    for r in routers:
+        app.include_router(r)
+
+    yield  # App's lifespan
+
+    await bot.session.close()  # D IE!!!!!!!!
+
+
+app = FastAPI(
+    title="Malenia API",
+    description="Payment webhook handler and user balance management",
+    version="1.0.0",
+    lifespan=lifespan,
+    docs_url="",
+)