fix: separate HWID device renewal flows

Keep one-off device top-ups scoped to the active subscription term and move device renewal into subscription checkout.

Carry HWID renewal metadata through provider callbacks and webhooks, including YooKassa saved-card flows.

Add admin extension controls, docs, demo data, and regression coverage.

backend/bot/payment_providers/base.py

@@ -114,6 +114,7 @@ class WebAppPaymentContext:
     sale_mode: str
     currency: str = "RUB"
     traffic_gb: Optional[float] = None
+    hwid_device_count: Optional[int] = None
     hwid_valid_from: Optional[Any] = None
     hwid_valid_until: Optional[Any] = None
     hwid_pricing_period_months: Optional[int] = None