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

demos/templates/insertr-config.template.json

@@ -0,0 +1,28 @@
+{
+  "site_name": "{{SITE_NAME}}",
+  "description": "{{SITE_DESCRIPTION}}",
+  "base_url": "{{BASE_URL}}",
+  "content_sections": [
+    {
+      "selector": ".hero-content",
+      "type": "markdown",
+      "editable": true,
+      "description": "Hero section content"
+    },
+    {
+      "selector": ".feature-block",
+      "type": "markdown", 
+      "editable": true,
+      "description": "Feature description blocks"
+    },
+    {
+      "selector": ".about-content",
+      "type": "markdown",
+      "editable": true,
+      "description": "About section content"
+    }
+  ],
+  "css_frameworks": ["{{CSS_FRAMEWORK}}"],
+  "complexity": "{{COMPLEXITY}}",
+  "testing_notes": "{{TESTING_NOTES}}"
+}