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

frontend/src/utils/basePath.js

@@ -0,0 +1,13 @@
+// Single source for the app's mount path. Vite injects import.meta.env.BASE_URL
+// from the build-time `base` (default '/', or e.g. '/ops/' for a subpath IIS
+// mount). Every root-absolute URL to a Flask-served asset or route must go
+// through withBase() so it resolves under the mount instead of the server root.
+export const BASE_URL = import.meta.env.BASE_URL
+
+// Prefix a root-absolute path (e.g. '/ge-aerospace-logo.svg', '/api', '/tv')
+// with the mount base. Leaves full URLs (http, data:) untouched.
+export function withBase(path) {
+  if (!path) return path
+  if (/^([a-z]+:)?\/\//i.test(path) || path.startsWith('data:')) return path
+  return BASE_URL + String(path).replace(/^\//, '')
+}