refactor: centralize Bot instantiation via create_bot() factory

Replace all ~45 direct Bot() calls across the codebase with a centralized
create_bot() factory function that automatically configures SOCKS5 proxy
session when PROXY_URL is set. This ensures proxy support applies uniformly
to all Telegram API traffic.

Key changes:
- Add app/bot_factory.py with create_bot() factory
- Replace direct Bot() instantiation in 33 files
- Fix session leaks in cloudpayments.py and auth.py (async with)
- Replace 2 direct httpx calls to api.telegram.org with
  bot.create_invoice_link() (balance.py, wheel.py)
- Remove now-unused imports (Bot, DefaultBotProperties, ParseMode, httpx)

main.py

@@ -964,11 +964,10 @@ async def _send_crash_notification_on_error(error: Exception) -> None:
         return
 
     try:
-        from aiogram import Bot
-
+        from app.bot_factory import create_bot
         from app.services.startup_notification_service import send_crash_notification
 
-        bot = Bot(token=settings.BOT_TOKEN)
+        bot = create_bot()
         try:
             traceback_str = traceback.format_exc()
             await send_crash_notification(bot, error, traceback_str)