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

cmd/root.go

@@ -52,7 +52,6 @@ func init() {
 
 	rootCmd.AddCommand(enhanceCmd)
 	rootCmd.AddCommand(serveCmd)
-	rootCmd.AddCommand(restoreCmd)
 }
 
 func initConfig() {