Enhance map functionality and API documentation

- Updated API documentation for the `rebuildZooms` endpoint to clarify its long execution time and response behavior.
- Modified MapView component to manage tile cache invalidation after rebuilding zoom levels, ensuring fresh tile display.
- Introduced a new composable for handling tile cache invalidation state after admin actions.
- Enhanced character icon creation to reflect ownership status with distinct colors.
- Improved loading state handling in various components for better user experience during data fetching.

frontend-nuxt/pages/admin/index.vue

@@ -389,11 +389,14 @@ function confirmRebuildZooms() {
   rebuildModalRef.value?.showModal()
 }
 
+const { markRebuildDone } = useRebuildZoomsInvalidation()
+
 async function doRebuildZooms() {
   rebuildModalRef.value?.close()
   rebuilding.value = true
   try {
     await api.adminRebuildZooms()
+    markRebuildDone()
     toast.success('Zooms rebuilt.')
   } catch (e) {
     toast.error((e as Error)?.message ?? 'Failed to rebuild zooms.')