Simplify script injection to single script with data attribute configuration

- Replace dual script injection (external + inline) with single script approach
- Pass site configuration via data attributes instead of inline JavaScript
- Update library auto-initialization to read config from script data attributes
- Reduce HTML bloat by eliminating 30+ lines of inline initialization code
- Maintain future-proof CDN compatibility and duplication prevention

Enhanced files now contain only one clean script tag with configuration.

internal/engine/injector.go

@@ -364,42 +364,8 @@ func (i *Injector) InjectEditorScript(doc *html.Node) {
 		return
 	}
 
-	// Create script element that loads insertr.js from our server
-	scriptHTML := fmt.Sprintf(`<script src="http://localhost:8080/insertr.js" data-insertr-injected="true"></script>
-<script type="text/javascript" data-insertr-injected="true">
-// Initialize insertr for demo sites
-document.addEventListener('DOMContentLoaded', function() {
-    if (typeof window.Insertr !== 'undefined') {
-        console.log('✅ Insertr library loaded successfully');
-        
-        // The library has auto-initialization, but we can force initialization
-        // with our demo configuration
-        window.Insertr.init({
-            siteId: '%s',
-            apiEndpoint: 'http://localhost:8080/api/content',
-            mockAuth: true, // Use mock authentication for demos
-            debug: true
-        });
-        
-        console.log('✅ Insertr initialized for demo site with config:', {
-            siteId: '%s',
-            apiEndpoint: 'http://localhost:8080/api/content',
-            mockAuth: true
-        });
-    } else {
-        console.error('❌ Insertr library failed to load');
-        
-        // Fallback for demo gates if library fails
-        const gates = document.querySelectorAll('.insertr-gate');
-        gates.forEach(gate => {
-            gate.addEventListener('click', function(e) {
-                e.preventDefault();
-                alert('🚧 Insertr library not loaded\\n\\nPlease run "just build-lib" to build the library first.');
-            });
-        });
-    }
-});
-</script>`, i.siteID, i.siteID)
+	// Create script element that loads insertr.js from our server with site configuration
+	scriptHTML := fmt.Sprintf(`<script src="http://localhost:8080/insertr.js" data-insertr-injected="true" data-site-id="%s" data-api-endpoint="http://localhost:8080/api/content" data-mock-auth="true" data-debug="true"></script>`, i.siteID)
 
 	// Parse and inject the script
 	scriptDoc, err := html.Parse(strings.NewReader(scriptHTML))
@@ -414,7 +380,7 @@ document.addEventListener('DOMContentLoaded', function() {
 		return
 	}
 
-	log.Printf("✅ Insertr.js library and initialization script injected")
+	log.Printf("✅ Insertr.js library injected with site configuration")
 }
 
 // injectAllScriptElements finds and injects all script elements from parsed HTML