feat: implement flexible editor gate system

- Replace automatic auth controls with developer-placed .insertr-gate elements
- Add OAuth-ready authentication flow with mock implementation
- Support any HTML element as gate with custom styling
- Implement proper gate restoration after authentication
- Move auth controls to bottom-right corner for better UX
- Add editor gates to demo pages (footer link and styled button)
- Maintain gates visible by default with hideGatesAfterAuth option
- Prevent duplicate authentication attempts with loading states

This enables small business owners to access editor via discrete
footer links or custom-styled elements placed anywhere by developers.

insertr-cli/pkg/content/enhancer.go

@@ -69,7 +69,7 @@ func (e *Enhancer) EnhanceFile(inputPath, outputPath string) error {
 	}
 
 	// Inject editor assets for development
-	libraryScript := GetLibraryScript(true) // Use minified for better performance
+	libraryScript := GetLibraryScript(false) // Use non-minified for development debugging
 	e.injector.InjectEditorAssets(doc, true, libraryScript)
 
 	// Write enhanced HTML