Fix demo site auto-enhancement and content persistence

- Restructure demo directory from test-sites/ to demos/ with flattened layout
- Add auto-enhancement on server startup for all sites with auto_enhance: true
- Fix inconsistent content ID generation that prevented dan-eden-portfolio content persistence
- Update server configuration to enhance from source to separate output directories
- Remove manual enhancement from justfile in favor of automatic server enhancement
- Clean up legacy test files and unused restore command
- Update build system to use CDN endpoint instead of file copying

lib/package.json

@@ -10,9 +10,8 @@
     "src/"
   ],
   "scripts": {
-    "build": "rollup -c && npm run copy:demo",
+    "build": "rollup -c",
     "build:only": "rollup -c",
-    "copy:demo": "cp dist/insertr.js ../test-sites/demo-site/insertr.js",
     "watch": "rollup -c -w",
     "dev": "rollup -c -w"
   },