feat(payments): implement server-side price resolution for subscription payments

Add a new function `resolve_fiat_offer_price_for_user` to determine the correct offer price for users based on their subscription choices and any applicable discounts. Update payment handlers for CryptoPay, FreeKassa, Platega, SeverPay, and YooKassa to utilize this function, ensuring callback price validation and improving error handling for price mismatches. This enhances security by preventing callback payload tampering and ensures accurate pricing for users.

bot/handlers/user/subscription/payments_platega.py

@@ -14,6 +14,8 @@ from db.dal import payment_dal
 router = Router(name="user_subscription_payments_platega_router")
 
 
+from bot.handlers.user.subscription.payments_subscription import resolve_fiat_offer_price_for_user
+
 @router.callback_query(F.data.startswith("pay_platega:"))
 async def pay_platega_callback_handler(
     callback: types.CallbackQuery,
@@ -50,7 +52,7 @@ async def pay_platega_callback_handler(
         _, data_payload = callback.data.split(":", 1)
         parts = data_payload.split(":")
         months = float(parts[0])
-        price_rub = float(parts[1])
+        callback_price_rub = float(parts[1])
         sale_mode = parts[2] if len(parts) > 2 else "subscription"
     except (ValueError, IndexError):
         logging.error(f"Invalid pay_platega data in callback: {callback.data}")
@@ -61,6 +63,43 @@ async def pay_platega_callback_handler(
         return
 
     user_id = callback.from_user.id
+    resolved_price_rub = await resolve_fiat_offer_price_for_user(
+        session=session,
+        settings=settings,
+        user_id=user_id,
+        months=months,
+        sale_mode=sale_mode,
+        promo_code_service=promo_code_service,
+    )
+    if resolved_price_rub is None:
+        logging.warning(
+            "Platega: no server-side price for user %s, value=%s, mode=%s",
+            user_id,
+            months,
+            sale_mode,
+        )
+        try:
+            await callback.answer(get_text("error_try_again"), show_alert=True)
+        except Exception as exc:
+            logging.debug("Suppressed exception in bot/handlers/user/subscription/payments_platega.py: %s", exc)
+        return
+
+    if abs(resolved_price_rub - callback_price_rub) > 0.01:
+        logging.warning(
+            "Platega: callback price mismatch for user %s, value=%s, mode=%s, callback=%.2f, resolved=%.2f",
+            user_id,
+            months,
+            sale_mode,
+            callback_price_rub,
+            resolved_price_rub,
+        )
+        try:
+            await callback.answer(get_text("error_try_again"), show_alert=True)
+        except Exception as exc:
+            logging.debug("Suppressed exception in bot/handlers/user/subscription/payments_platega.py: %s", exc)
+        return
+
+    price_rub = resolved_price_rub
     human_value = str(int(months)) if float(months).is_integer() else f"{months:g}"
     payment_description = (
         get_text("payment_description_traffic", traffic_gb=human_value)