fix(loyalty): route prefix, module migrations, and wallet barcode tests

- Fix 404 on /admin/loyalty/* and /vendor/loyalty/* by applying
  ROUTE_CONFIG custom_prefix when registering page routers in main.py
  (admin, vendor, and storefront registrations all updated)
- Move loyalty alembic migrations from central alembic/versions/ into
  app/modules/loyalty/migrations/versions/ with proper naming convention
- Add migrations_path="migrations" to loyalty module definition so
  the auto-discovery system finds them
- Add unit tests for Apple/Google Wallet Code 128 barcode configuration
  (6 Apple tests, 4 Google tests)
- Add integration tests for module migration auto-discovery (4 tests)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

main.py

@@ -349,10 +349,11 @@ admin_page_routes = get_admin_page_routes()
 logger.info(f"  Found {len(admin_page_routes)} admin page route modules")
 
 for route_info in admin_page_routes:
-    logger.info(f"  Registering {route_info.module_code} admin pages")
+    prefix = f"/admin{route_info.custom_prefix}" if route_info.custom_prefix else "/admin"
+    logger.info(f"  Registering {route_info.module_code} admin pages at {prefix}")
     app.include_router(
         route_info.router,
-        prefix="/admin",
+        prefix=prefix,
         tags=route_info.tags,
         include_in_schema=route_info.include_in_schema,
     )
@@ -365,10 +366,11 @@ vendor_page_routes = get_vendor_page_routes()
 logger.info(f"  Found {len(vendor_page_routes)} vendor page route modules")
 
 for route_info in vendor_page_routes:
-    logger.info(f"  Registering {route_info.module_code} vendor pages (priority={route_info.priority})")
+    prefix = f"/vendor{route_info.custom_prefix}" if route_info.custom_prefix else "/vendor"
+    logger.info(f"  Registering {route_info.module_code} vendor pages at {prefix} (priority={route_info.priority})")
     app.include_router(
         route_info.router,
-        prefix="/vendor",
+        prefix=prefix,
         tags=route_info.tags,
         include_in_schema=route_info.include_in_schema,
     )
@@ -386,10 +388,11 @@ logger.info(f"  Found {len(storefront_page_routes)} storefront page route module
 # Register at /storefront/* (direct access)
 logger.info("  Registering storefront routes at /storefront/*")
 for route_info in storefront_page_routes:
-    logger.info(f"    - {route_info.module_code} (priority={route_info.priority})")
+    prefix = f"/storefront{route_info.custom_prefix}" if route_info.custom_prefix else "/storefront"
+    logger.info(f"    - {route_info.module_code} at {prefix} (priority={route_info.priority})")
     app.include_router(
         route_info.router,
-        prefix="/storefront",
+        prefix=prefix,
         tags=["storefront-pages"],
         include_in_schema=False,
     )
@@ -397,9 +400,10 @@ for route_info in storefront_page_routes:
 # Register at /vendors/{code}/storefront/* (path-based development mode)
 logger.info("  Registering storefront routes at /vendors/{code}/storefront/*")
 for route_info in storefront_page_routes:
+    prefix = f"/vendors/{{vendor_code}}/storefront{route_info.custom_prefix}" if route_info.custom_prefix else "/vendors/{vendor_code}/storefront"
     app.include_router(
         route_info.router,
-        prefix="/vendors/{vendor_code}/storefront",
+        prefix=prefix,
         tags=["storefront-pages"],
         include_in_schema=False,
     )