Consolidate white_label to remove_branding and add embed widget

- Rename white_label feature to remove_branding across frontend/backend
- Update billing catalog, plan features, and permission checks
- Add dark mode support to Recharts tooltips with useDarkMode hook
- Create embeddable booking widget with EmbedBooking page
- Add EmbedWidgetSettings for generating embed code
- Fix Appearance settings page permission check
- Update test files for new feature naming
- Add notes field to User model

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/hooks/useBillingPlans.ts

@@ -280,7 +280,7 @@ export const PERMISSION_TO_FEATURE_CODE: Record<string, string> = {
   // Platform
   can_api_access: 'api_access',
   can_use_custom_domain: 'custom_domain',
-  can_white_label: 'white_label',
+  can_white_label: 'remove_branding',
 
   // Features
   can_accept_payments: 'payment_processing',
@@ -328,11 +328,8 @@ export function planFeaturesToLegacyPermissions(
       case 'custom_domain':
         permissions.can_use_custom_domain = value as boolean;
         break;
-      case 'white_label':
-        permissions.can_white_label = value as boolean;
-        break;
       case 'remove_branding':
-        permissions.can_white_label = permissions.can_white_label || (value as boolean);
+        permissions.can_white_label = value as boolean;
         break;
       case 'payment_processing':
         permissions.can_accept_payments = value as boolean;