refactor: Extract UI into dedicated control panel module

- Create InsertrControlPanel class for unified UI management
- Separate business logic from presentation layer
- Remove DOM manipulation from auth.js and editor.js
- Add comprehensive CSS for status indicators and editing effects
- Implement consistent kebab-case file naming
- Add event-driven communication between core and UI layers

UI Architecture:
- Unified control panel with status indicator and action buttons
- Color-coded status dots (gray/blue/green for visitor/auth/editing)
- Professional editing hover effects with tooltips
- Responsive design for mobile devices
- Proper z-index and accessibility management

Business Logic:
- Pure auth.js focused on authentication state and OAuth flows
- Pure editor.js focused on content editing workflow
- Event emitters for state changes between modules
- Clean separation of concerns and testable architecture

go.mod

@@ -15,7 +15,9 @@ require (
 )
 
 require (
+	github.com/coreos/go-oidc/v3 v3.15.0 // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
+	github.com/go-jose/go-jose/v4 v4.0.5 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
@@ -30,7 +32,9 @@ require (
 	github.com/subosito/gotenv v1.6.0 // indirect
 	go.uber.org/atomic v1.9.0 // indirect
 	go.uber.org/multierr v1.9.0 // indirect
+	golang.org/x/crypto v0.41.0 // indirect
 	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
+	golang.org/x/oauth2 v0.31.0 // indirect
 	golang.org/x/sys v0.35.0 // indirect
 	golang.org/x/text v0.28.0 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect