fix(google-maps): default mapId fallback to DEMO_MAP_ID

Google's pre-registered dev map ID. An arbitrary string like 'map'
triggers a console warning every load; DEMO_MAP_ID renders silently
and matches Google's documented convention for examples.

Author: harlan-zw

packages/script/src/runtime/components/GoogleMaps/ScriptGoogleMaps.vue

@@ -227,7 +227,7 @@ const options = computed(() => {
   // sets `styles`, we drop `mapId` so styles apply. Otherwise fall back to a map ID
   // so `AdvancedMarkerElement` can function. The marker component warns if markers
   // are mounted against a styled (mapId-less) map.
-  const mapId = props.mapOptions?.styles ? undefined : (currentMapId.value || 'map')
+  const mapId = props.mapOptions?.styles ? undefined : (currentMapId.value || 'DEMO_MAP_ID')
   return defu(
     { center: centerOverride.value, mapId },
     props.mapOptions,