Fixes for giftcards and phone input

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

@@ -3,6 +3,7 @@
 	import { toast } from 'svelte-sonner';
 	import { SvelteDate } from 'svelte/reactivity';
 	import { getLocalTimeZone } from '@internationalized/date';
+	import { isValidUKPhone, toE164UK } from '$lib/utils/phone';
 
 	// UI Components
 	import * as Modal from '$lib/components/ui/dialog';
@@ -51,6 +52,7 @@
 	let selectedUserId = $state<string | null>(null);
 	let guestName = $state('');
 	let guestPhone = $state('');
+	let guestPhoneError = $state('');
 	let loadingUsers = $state(false);
 
 	// Step 2: Services
@@ -279,7 +281,11 @@
 			let finalUserId = selectedUserId;
 
 			if (userType === 'guest') {
-				const phone = guestPhone.trim() || '+447700900000';
+				if (!isValidUKPhone(guestPhone)) {
+					toast.error('Please enter a valid UK phone number for the guest');
+					return;
+				}
+				const phone = toE164UK(guestPhone)!;
 				const createRes = await fetch('/api/users/guest', {
 					method: 'POST',
 					headers: {
@@ -545,9 +551,9 @@
 							<div class="max-h-[300px] overflow-y-auto rounded-md border border-gray-200">
 								{#if loadingUsers}
 									<div class="space-y-2 p-2">
-									{#each Array(3) as _, i (i)}
-										<Skeleton class="h-10 w-full" />
-									{/each}
+										{#each Array(3) as _, i (i)}
+											<Skeleton class="h-10 w-full" />
+										{/each}
 									</div>
 								{:else if users.length === 0}
 									<div class="flex items-center justify-center p-8 text-sm text-gray-500">
@@ -622,8 +628,13 @@
 										class="flex h-10 w-full rounded-md border border-input bg-background px-3 py-2 text-sm ring-offset-background focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 focus-visible:outline-none"
 										placeholder="07700 900000 (optional — helps us reach you if running late)"
 										value={guestPhone}
-										oninput={(e) => (guestPhone = e.currentTarget.value)}
+										oninput={(e) => { guestPhone = e.currentTarget.value; }}
+										onblur={() => { guestPhoneError = guestPhone && !isValidUKPhone(guestPhone) ? 'Invalid UK phone number' : ''; }}
+										class={guestPhoneError ? 'border-red-500' : ''}
 									/>
+									{#if guestPhoneError}
+										<p class="mt-1 text-xs text-red-600">{guestPhoneError}</p>
+									{/if}
 								</div>
 								<p class="rounded-lg bg-yellow-50 p-3 text-sm text-yellow-800">
 									Booking as a guest creates a temporary record. Encourage them to sign up for