chore: annotate XTR provider_token and add missing return type

bot/app/web/subscription_webapp.py

@@ -2472,7 +2472,7 @@ async def _create_stars_payment(
                 title=description,
                 description=description,
                 payload=payload,
-                provider_token="",
+                provider_token="",  # Required to be empty for Telegram Stars (XTR) per Telegram Bot API.
                 currency="XTR",
                 prices=prices,
             )

db/dal/subscription_dal.py

@@ -130,7 +130,7 @@ async def upsert_subscription(session: AsyncSession,
 
 async def deactivate_other_active_subscriptions(
         session: AsyncSession, panel_user_uuid: str,
-        current_panel_subscription_uuid: Optional[str]):
+        current_panel_subscription_uuid: Optional[str]) -> None:
     stmt = (update(Subscription).where(
         Subscription.panel_user_uuid == panel_user_uuid,
         Subscription.is_active == True,