refactor(promo): streamline discount consumption logic

Simplify the discount consumption process in the PromoCodeService by removing unnecessary checks for active discounts and improving logging for various scenarios. Ensure that successful payments are always accounted for, even if the associated reservation has expired. This enhances clarity and reliability in the discount application workflow.

db/alembic_runner.py

@@ -257,6 +257,12 @@ async def run_alembic_migrations(settings: Settings, async_engine: AsyncEngine)
     """Apply Alembic migrations with bootstrap for existing installations."""
 
     alembic_config = _build_alembic_config(settings)
+    allow_bootstrap_without_legacy = os.getenv("ALEMBIC_ALLOW_STAMP_WITHOUT_LEGACY", "").lower() in {
+        "1",
+        "true",
+        "yes",
+        "on",
+    }
 
     async with async_engine.begin() as async_connection:
         (
@@ -268,17 +274,24 @@ async def run_alembic_migrations(settings: Settings, async_engine: AsyncEngine)
         )
 
         if not has_alembic_version and has_users_table:
-            if not has_legacy_migrator_table:
+            if not has_legacy_migrator_table and not allow_bootstrap_without_legacy:
                 raise RuntimeError(
                     "Alembic bootstrap refused: found existing users table without "
                     "alembic_version and without legacy schema_migrations marker. "
-                    "Cannot safely determine migration baseline."
+                    "Set ALEMBIC_ALLOW_STAMP_WITHOUT_LEGACY=true to explicitly allow "
+                    f"stamping baseline {_BASELINE_REVISION} after manual verification."
                 )
 
-            logging.info(
-                "Alembic: applying legacy migrator compatibility fixes before stamp."
-            )
-            await async_connection.run_sync(_run_legacy_migrator_compatibility)
+            if has_legacy_migrator_table:
+                logging.info(
+                    "Alembic: applying legacy migrator compatibility fixes before stamp."
+                )
+                await async_connection.run_sync(_run_legacy_migrator_compatibility)
+            else:
+                logging.warning(
+                    "Alembic: existing users table without legacy schema_migrations; "
+                    "proceeding with explicit bootstrap override flag."
+                )
 
             logging.info(
                 "Alembic: existing schema detected without alembic_version; stamping %s.",