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/stores/theme.js

@@ -0,0 +1,39 @@
+import { ref, watch } from 'vue'
+
+const STORAGE_KEY = 'shopdb-theme'
+
+// Get initial theme from localStorage or system preference
+function getInitialTheme() {
+  const stored = localStorage.getItem(STORAGE_KEY)
+  if (stored) return stored
+
+  // Fall back to system preference
+  if (window.matchMedia('(prefers-color-scheme: dark)').matches) {
+    return 'dark'
+  }
+  return 'light'
+}
+
+export const currentTheme = ref(getInitialTheme())
+
+// Apply theme to document
+function applyTheme(theme) {
+  document.documentElement.setAttribute('data-theme', theme)
+  localStorage.setItem(STORAGE_KEY, theme)
+}
+
+// Initialize on load
+applyTheme(currentTheme.value)
+
+// Watch for changes
+watch(currentTheme, (newTheme) => {
+  applyTheme(newTheme)
+})
+
+export function toggleTheme() {
+  currentTheme.value = currentTheme.value === 'dark' ? 'light' : 'dark'
+}
+
+export function setTheme(theme) {
+  currentTheme.value = theme
+}