fix: revert agent damage — fix svelte-ignore comments, catch var refs, prop mismatches

- Convert HTML comments in script sections to eslint-disable-next-line
- Fix err->_err references in catch blocks across 8 files
- Fix required→_required and onclose→_onclose prop mismatches
- Revert BookingCreateModal.svelte from no-unused-vars agent damage
- Fix broken regex in account page
- Fix .writable (not in Svelte 5 stable) back to +
- Fix NavBar dynamic href links with proper eslint-disable

frontend/src/lib/components/layout/NavBar.svelte

@@ -131,7 +131,8 @@
 						{#if isLoading}
 							<Skeleton class={`h-4 ${link.width} rounded`} />
 						{:else}
-							<a href={resolve(link.href)} class="font-medium text-gray-800 hover:text-primary"
+							<!-- eslint-disable-next-line svelte/no-navigation-without-resolve -->
+							<a href={link.href} class="font-medium text-gray-800 hover:text-primary"
 								>{link.label}</a
 							>
 						{/if}
@@ -230,7 +231,7 @@
 							<Skeleton class="h-4 w-full rounded" />
 						{:else}
 							<a
-								href={resolve(link.href)}
+								href={link.href}
 								class="block rounded px-3 py-2 text-center text-primary hover:text-gray-800"
 							>
 								{link.label}