feat: widget additional services — sourced from rental objects module

- Additional services in widget are now derived from rental_objects (not a separate list)
- Settings page shows rental objects with enable/disable toggle; link to rental module
- Saves only {id, enabled}[] to widget_services — rental objects manage name/price/icon
- Standalone widget also derives additionalServices from config.rentalObjects
- Widget config API includes services[] in widgetSettings

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/api.ts

@@ -1716,6 +1716,7 @@ export interface WidgetConfig {
     allowExtraBeds: boolean
     allowChildren: boolean
     hotelName: string
+    services?: { id: string; enabled: boolean }[]
   }
 }