Initial import: shopdb-flask multi-site asset platform

Flask + Vue rewrite of the classic-ASP shopdb, built as a plugin
framework so sister GE Aerospace sites can adopt it. Product version
0.7.0-pre-0.8.0, plugin contract 0.11.0, 966 backend tests.

Key entry points:
- docs/INSTALL-WINDOWS-IIS.md - tested Windows + IIS install runbook
  (own-site and subpath deployment methods)
- docs/PILOT-DEPLOY.md - production pilot: stand up + import + verify
- docs/IMPORT-API.md - schema-agnostic legacy data import contract
- scripts/site_imports/wjf/ - West Jefferson reference import loader
- docs/adr/ - twelve accepted architecture decision records

shopdb/utils/__init__.py

@@ -0,0 +1,20 @@
+"""Utility modules."""
+
+from .responses import (
+    api_response,
+    success_response,
+    error_response,
+    paginated_response,
+    ErrorCodes
+)
+from .pagination import get_pagination_params, paginate_query
+
+__all__ = [
+    'api_response',
+    'success_response',
+    'error_response',
+    'paginated_response',
+    'ErrorCodes',
+    'get_pagination_params',
+    'paginate_query'
+]