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

plugins/knowledgebase/migrations/env.py

@@ -0,0 +1,14 @@
+"""Alembic environment for the knowledgebase plugin migration chain.
+
+Delegates to the shared runner in shopdb.plugins.alembic_template, which
+filters the metadata to this plugin's tables and drives Alembic against the
+per-plugin version table alembic_version_knowledgebase. See ADR-008 for the
+ownership cutover between the core chain and per-plugin chains.
+"""
+import os
+
+os.environ['PLUGIN_NAME'] = 'knowledgebase'
+
+from shopdb.plugins.alembic_template import run_migrations  # noqa: E402
+
+run_migrations()