Maintenance page called useMaintenanceRecords() without a vehicleId,
causing the schedules query (enabled: !!vehicleId) to never execute.
Added vehicle selector to both desktop and mobile pages, auto-selects
first vehicle, and passes selectedVehicleId to the hook. Also fixed
stale query invalidation keys in delete handlers.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>