Update project structure and enhance frontend functionality

- Added a new AGENTS.md file to document the project structure and conventions.
- Updated .gitignore to include node_modules and refined cursor rules.
- Introduced new backend and frontend components for improved map interactions, including context menus and controls.
- Enhanced API composables for better admin and authentication functionalities.
- Refactored existing components for cleaner code and improved user experience.
- Updated README.md to clarify production asset serving and user setup instructions.

frontend-nuxt/app.vue

@@ -19,7 +19,8 @@
 // Global error handling: on API auth failure, redirect to login
 const { onApiError } = useMapApi()
 const { fullUrl } = useAppPaths()
-onApiError(() => {
+const unsubscribe = onApiError(() => {
   if (import.meta.client) window.location.href = fullUrl('/login')
 })
+onUnmounted(() => unsubscribe())
 </script>