fix: enforce derived validation onblur in patch tests modal to block invalid submissions

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

@@ -45,15 +45,35 @@ import { Button } from '$lib/components/ui/button';
 		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 === '');
+	function validateNameField() {
+		formErrors.name = !formData.name.trim() ? 'Name is required' : '';
 	}
 
+	function validateNoticeDurationField() {
+		formErrors.notice_duration = (formData.notice_duration_hours < 0 || isNaN(formData.notice_duration_hours)) ? 'Must be a positive number' : '';
+	}
+
+	function validateExpiryField() {
+		formErrors.expiry = (formData.expiry_months < 1 || isNaN(formData.expiry_months)) ? 'Must be at least 1 month' : '';
+	}
+
+	function validateAllFields() {
+		validateNameField();
+		validateNoticeDurationField();
+		validateExpiryField();
+	}
+
+	let isFormValid = $derived(
+		formData.name.trim() !== '' &&
+		!formErrors.name &&
+		!formErrors.notice_duration &&
+		!formErrors.expiry &&
+		formData.notice_duration_hours >= 0 &&
+		!isNaN(formData.notice_duration_hours) &&
+		formData.expiry_months >= 1 &&
+		!isNaN(formData.expiry_months)
+	);
+
 	async function fetchData() {
 		loading = true;
 		try {
@@ -94,6 +114,11 @@ import { Button } from '$lib/components/ui/button';
 			expiry_months: 6,
 			service_ids: []
 		};
+		formErrors = {
+			name: '',
+			notice_duration: '',
+			expiry: ''
+		};
 		isEditing = false;
 	}
 
@@ -111,6 +136,11 @@ import { Button } from '$lib/components/ui/button';
 			expiry_months: pt.expiry_months,
 			service_ids: pt.service_ids || []
 		};
+		formErrors = {
+			name: '',
+			notice_duration: '',
+			expiry: ''
+		};
 		isEditing = true;
 		showModal = true;
 	}
@@ -124,8 +154,9 @@ import { Button } from '$lib/components/ui/button';
 	}
 
 	async function savePatchTest() {
-		if (!formData.name.trim()) {
-			toast.error('Patch test name is required');
+		validateAllFields();
+		if (!isFormValid) {
+			toast.error('Please fix validation errors before submitting');
 			return;
 		}
 
@@ -346,6 +377,7 @@ import { Button } from '$lib/components/ui/button';
 					type="text"
 					placeholder="e.g. Standard Glue Patch Test"
 					bind:value={formData.name}
+					onblur={validateNameField}
 					class="w-full {formErrors.name ? 'border-red-500' : ''}"
 				/>
 				{#if formErrors.name}
@@ -373,6 +405,7 @@ import { Button } from '$lib/components/ui/button';
 						inputmode="numeric"
 						min="0"
 						bind:value={formData.notice_duration_hours}
+						onblur={validateNoticeDurationField}
 						class="w-full {formErrors.notice_duration ? 'border-red-500' : ''}"
 					/>
 					{#if formErrors.notice_duration}
@@ -389,6 +422,7 @@ import { Button } from '$lib/components/ui/button';
 						inputmode="numeric"
 						min="1"
 						bind:value={formData.expiry_months}
+						onblur={validateExpiryField}
 						class="w-full {formErrors.expiry ? 'border-red-500' : ''}"
 					/>
 					{#if formErrors.expiry}
@@ -424,10 +458,8 @@ import { Button } from '$lib/components/ui/button';
 				Cancel
 			</Button>
 			<Button 
-				onclick={() => {
-					if (validateForm()) savePatchTest();
-				}} 
-				disabled={isSubmitting}
+				onclick={savePatchTest} 
+				disabled={isSubmitting || !isFormValid}
 			>
 				{isSubmitting ? 'Saving...' : 'Save'}
 			</Button>