fix: validate Patch Test modal inputs

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

@@ -39,6 +39,21 @@ import { Button } from '$lib/components/ui/button';
 		service_ids: [] as string[]
 	});
 
+	let formErrors = $state({
+		name: '',
+		notice_duration: '',
+		expiry: ''
+	});
+
+	function validateForm(): boolean {
+		formErrors = {
+			name: !formData.name.trim() ? 'Name is required' : '',
+			notice_duration: (formData.notice_duration_hours < 0 || isNaN(formData.notice_duration_hours)) ? 'Must be a positive number' : '',
+			expiry: (formData.expiry_months < 1 || isNaN(formData.expiry_months)) ? 'Must be at least 1 month' : ''
+		};
+		return Object.values(formErrors).every(err => err === '');
+	}
+
 	async function fetchData() {
 		loading = true;
 		try {
@@ -331,8 +346,11 @@ import { Button } from '$lib/components/ui/button';
 					type="text"
 					placeholder="e.g. Standard Glue Patch Test"
 					bind:value={formData.name}
-					class="w-full"
+					class="w-full {formErrors.name ? 'border-red-500' : ''}"
 				/>
+				{#if formErrors.name}
+					<p class="text-xs text-red-600">{formErrors.name}</p>
+				{/if}
 			</div>
 
 			<div class="space-y-2">
@@ -354,8 +372,11 @@ import { Button } from '$lib/components/ui/button';
 						type="number"
 						min="0"
 						bind:value={formData.notice_duration_hours}
-						class="w-full"
+						class="w-full {formErrors.notice_duration ? 'border-red-500' : ''}"
 					/>
+					{#if formErrors.notice_duration}
+						<p class="text-xs text-red-600">{formErrors.notice_duration}</p>
+					{/if}
 					<p class="text-xs text-gray-500">Hours prior to booking required</p>
 				</div>
 
@@ -366,8 +387,11 @@ import { Button } from '$lib/components/ui/button';
 						type="number"
 						min="1"
 						bind:value={formData.expiry_months}
-						class="w-full"
+						class="w-full {formErrors.expiry ? 'border-red-500' : ''}"
 					/>
+					{#if formErrors.expiry}
+						<p class="text-xs text-red-600">{formErrors.expiry}</p>
+					{/if}
 					<p class="text-xs text-gray-500">How long the test remains valid</p>
 				</div>
 			</div>
@@ -397,7 +421,12 @@ import { Button } from '$lib/components/ui/button';
 			<Button variant="outline" onclick={() => (showModal = false)} disabled={isSubmitting}>
 				Cancel
 			</Button>
-			<Button onclick={savePatchTest} disabled={isSubmitting || !formData.name.trim()}>
+			<Button 
+				onclick={() => {
+					if (validateForm()) savePatchTest();
+				}} 
+				disabled={isSubmitting}
+			>
 				{isSubmitting ? 'Saving...' : 'Save'}
 			</Button>
 		</Modal.Footer>