fix(payments): enhance payment processing return values

Refactor the `process_successful_payment` function to ensure consistent return values, replacing `return` statements with `return False` for error cases. This improves error handling and clarity in payment processing logic. Additionally, update the promo code consumption logic to handle missing discounts more gracefully, ensuring proper logging and flow control.

bot/services/promo_code_service.py

@@ -407,20 +407,26 @@ class PromoCodeService:
             user_id,
             include_expired=True,
         )
-        if active_discount and active_discount.promo_code_id != promo_code_id:
+        now_utc = datetime.now(timezone.utc)
+
+        if not active_discount:
             logging.info(
-                "Active discount promo %s differs from payment promo %s; leaving active discount intact.",
+                "Discount reservation missing at consumption time (user=%s, promo=%s, payment=%s)",
+                user_id,
+                promo_code_id,
+                payment_id,
+            )
+            return False
+
+        if active_discount.promo_code_id != promo_code_id:
+            logging.info(
+                "Active discount promo %s differs from payment promo %s; skipping consumption.",
                 active_discount.promo_code_id,
                 promo_code_id,
             )
-            active_discount = None
+            return False
 
-        now_utc = datetime.now(timezone.utc)
-        if (
-            active_discount
-            and active_discount.promo_code_id == promo_code_id
-            and active_discount.expires_at <= now_utc
-        ):
+        if active_discount.expires_at <= now_utc:
             logging.info(
                 "Discount reservation expired before payment consumption (user=%s, promo=%s)",
                 user_id,
@@ -466,8 +472,11 @@ class PromoCodeService:
                 )
                 return False
 
-        if active_discount and active_discount.promo_code_id == promo_code_id:
-            await active_discount_dal.clear_active_discount(session, user_id)
+        await active_discount_dal.clear_active_discount_if_matches(
+            session,
+            user_id=user_id,
+            promo_code_id=promo_code_id,
+        )
 
         await session.flush()
         logging.info(