fix(frontend): Svelte 5 reactivity, each block keys, and path resolution

Add proper keys to #each blocks across 15+ components to fix reordering bugs. Replace new Date() with SvelteDate in reactive contexts. Use $derived for computed values (totalPages). Use resolve() from $app/paths for all internal navigation hrefs. Add ARIA labels and keyboard accessibility to NavBar mobile menu. Remove unused handleRetry from UserPaymentModal.

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

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

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

@@ -41,11 +41,11 @@
 	let creatingService = $state(false);
 	let serviceErrors = $state<Record<string, string>>({});
 
-	function validatePrice(price: any): string {
+	function validatePrice(price: number | string): string {
 		if (price === null || price === undefined || price === '') {
 			return 'Price is required';
 		}
-		const numPrice = parseFloat(price);
+		const numPrice = parseFloat(typeof price === 'number' ? price.toString() : price);
 		if (isNaN(numPrice)) {
 			return 'Price must be a valid number';
 		}
@@ -62,7 +62,7 @@
 		return '';
 	}
 
-	function validateDuration(value: any, field: string): string {
+	function validateDuration(value: number | string, field: string): string {
 		if (value === null || value === undefined || value === '') {
 			return 'Field cannot be empty';
 		}