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/admin/BookingCreateModal.svelte

@@ -146,6 +146,8 @@
 			!customServiceErrors.minimum_age_required
 	);
 
+	function toggleCustomForm(show: boolean) {
+		showCustomCreateForm = show;
 		if (show) {
 			newCustomService = {
 				name: '',
@@ -324,6 +326,7 @@
 			: !!(guestName.trim() && guestPhone.trim() && isValidUKPhone(guestPhone))
 	);
 	const canProceedStep2 = $derived(selectedServices.length > 0);
+	const canProceedStep3 = $derived(true); // Overrides are optional
 	const canProceedStep4 = $derived(!!(selectedDate && selectedTime));
 
 	/** Whether the currently selected time slot is out-of-hours */
@@ -484,7 +487,7 @@
 					(user: { account_role: string }) => !excludedRoles.includes(user.account_role)
 				);
 			}
-		} catch (_err) {
+		} catch (err) {
 			toast.error('Failed to load users');
 		} finally {
 			loadingUsers = false;
@@ -505,7 +508,7 @@
 			if (response.ok) {
 				services = await response.json();
 			}
-		} catch (_err) {
+		} catch (err) {
 			toast.error('Failed to load services');
 		} finally {
 			loadingServices = false;
@@ -579,7 +582,7 @@
 				workingHours = { ...workingHours, ...whMap };
 				availableHours = { ...availableHours, ...ahMap };
 			}
-		} catch (_err) {
+		} catch (err) {
 			toast.error('Failed to load availability');
 		} finally {
 			_loadingWorkingHours = false;
@@ -649,7 +652,7 @@
 				workingHours = { ...workingHours, ...whMap };
 				availableHours = { ...availableHours, ...ahMap };
 			}
-		} catch (_err) {
+		} catch (err) {
 			toast.error('Failed to load availability');
 		} finally {
 			_loadingWorkingHours = false;
@@ -739,7 +742,7 @@
 				toast.error(`Failed to reserve slot: ${errorText}`);
 				return false;
 			}
-		} catch (_err) {
+		} catch (err) {
 			toast.error('Failed to reserve slot');
 			return false;
 		} finally {
@@ -1039,7 +1042,7 @@
 				const errorText = await res.text();
 				toast.error(`Failed to create booking: ${errorText}`);
 			}
-		} catch (_err) {
+		} catch (err) {
 			toast.error('An error occurred while creating booking');
 		} finally {
 			submitting = false;