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

scripts/dev.js

@@ -39,8 +39,8 @@ const commands = {
       
       // Check files exist
       const requiredFiles = [
-        'test-sites/demo-site/index.html',
-        'test-sites/demo-site/about.html', 
+        'demos/demo-site/index.html',
+        'demos/demo-site/about.html', 
         'lib/dist/insertr.js',
         'lib/dist/insertr.min.js',
         'cmd/serve.go',
@@ -77,8 +77,8 @@ const commands = {
         console.log('\n📊 Project stats:');
         
         // Count editable elements
-        const indexContent = fs.readFileSync('test-sites/demo-site/index.html', 'utf8');
-        const aboutContent = fs.readFileSync('test-sites/demo-site/about.html', 'utf8');
+        const indexContent = fs.readFileSync('demos/demo-site/index.html', 'utf8');
+        const aboutContent = fs.readFileSync('demos/demo-site/about.html', 'utf8');
         const insertrMatches = (indexContent + aboutContent).match(/class="insertr"/g) || [];
         console.log(`   📝 Editable elements: ${insertrMatches.length}`);