feat: Unified FeaturesPermissionsEditor component for plan and business permissions

- Create reusable FeaturesPermissionsEditor component with support for both
  subscription plan editing and individual business permission overrides
- Add can_use_contracts field to Tenant model for per-business contracts toggle
- Update PlatformSettings.tsx to use unified component for plan permissions
- Update BusinessEditModal.tsx to use unified component for business permissions
- Update PlatformBusinessUpdate API interface with all permission fields
- Add contracts permission mapping to tenant sync task

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

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

frontend/src/api/platform.ts

@@ -41,11 +41,38 @@ export interface PlatformBusinessUpdate {
   subscription_tier?: string;
   max_users?: number;
   max_resources?: number;
+  // Platform permissions
   can_manage_oauth_credentials?: boolean;
   can_accept_payments?: boolean;
   can_use_custom_domain?: boolean;
   can_white_label?: boolean;
   can_api_access?: boolean;
+  // Feature permissions
+  can_add_video_conferencing?: boolean;
+  can_connect_to_api?: boolean;
+  can_book_repeated_events?: boolean;
+  can_require_2fa?: boolean;
+  can_download_logs?: boolean;
+  can_delete_data?: boolean;
+  can_use_sms_reminders?: boolean;
+  can_use_masked_phone_numbers?: boolean;
+  can_use_pos?: boolean;
+  can_use_mobile_app?: boolean;
+  can_export_data?: boolean;
+  can_use_plugins?: boolean;
+  can_use_tasks?: boolean;
+  can_create_plugins?: boolean;
+  can_use_webhooks?: boolean;
+  can_use_calendar_sync?: boolean;
+  can_use_contracts?: boolean;
+  can_process_refunds?: boolean;
+  can_create_packages?: boolean;
+  can_use_email_templates?: boolean;
+  can_customize_booking_page?: boolean;
+  advanced_reporting?: boolean;
+  priority_support?: boolean;
+  dedicated_support?: boolean;
+  sso_enabled?: boolean;
 }
 
 export interface PlatformBusinessCreate {