feat(frontend): add custom services management UI components

Add CustomServicesManagement component for CRUD operations on custom services. Update BookingCreateModal, WalkInCreateModal, and BookingsCard to support custom service selection. Minor improvements to ServicesManagement and ImageUpload.

Ultraworked with Sisyphus (https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

frontend/src/lib/components/admin/ImageUpload.svelte

@@ -4,7 +4,6 @@
 	import FileDropZone from '$lib/components/ui/file-drop-zone.svelte';
 	import { authStore } from '$lib/stores/auth.svelte';
 	import * as AlertDialog from '$lib/components/ui/alert-dialog';
-	import heic2any from 'heic2any';
 
 	// =============== Image Upload ===============
 	let uploading = $state(false);
@@ -50,6 +49,7 @@
 	}
 
 	async function convertHeicToPng(file: File): Promise<File> {
+		const heic2any = (await import('heic2any')).default;
 		const result = await heic2any({ blob: file, toType: 'image/png' });
 		const blob = Array.isArray(result) ? result[0] : result;
 		const pngName = file.name.replace(/\.(heic|heif)$/i, '.png');