Gift-card rolling expiry, SvelteDate→Date purge, strict DST tests, UTC scan-location + settings legal floor

Gift-card rolling expiry (setting-driven, was dead config):
- GetGiftCardExpiryMonths(): single source of truth (business_settings
  gift_card_expiry_months, fallback 24) shared by payment handlers and the
  CleanupExpiredGiftCards job (was hardcoded 24).
- expiry_date now maintained on ALL 9 gift-card write sites (buy, topup,
  transfer, redeem, terminal payment, refund credit, till) so the refund-time
  guard at refunds.go actually fires. Schema default 12->24 + migration note;
  test-DB seed aligned. Stale "expiry_date IS NULL" test rewritten; new
  expired-card-rejected regression test.

Frontend SvelteDate purge (docs' stated convention, wide):
- All 180+ raw `new SvelteDate(...)` uses across routes/components replaced
  with parseWallClockDate (backend UTC ISO) or new Date (wall-clock
  constructors). SvelteDate imports removed. timeSlots.ts getDayWithOrdinal
  fixed. Zero SvelteDate references remain; svelte-check clean.

Strict timezone/DST testing + QA fixes:
- 8 new hermetic boundary tests: clock.DST transitions (both 2026 folds),
  closing-hours GMT vs BST, booking date-window midnight, refund-tier
  elapsed-time independence, deposit-window UTC-instant, scheduling
  LondonDateString midnight, today AT TIME ZONE window + UTC round-trip.
- today.go summary date labels fixed to London wall-clock (were showing the
  previous UTC day during BST) + regression test.
- pgx ScanLocation fixed to UTC via AfterConnect (was host-local -> JSON
  offsets depended on deployment TZ, contradicting the documented UTC
  invariant) + regression test. Registered as a new *Type to avoid a data
  race on the shared type map (caught by -race).

Admin Business Settings (setting now functional => legal floor):
- gift_card_expiry_months validation floor raised 1 -> 12 months (CMA/
  Consumer Rights Act 2015 unfair-contract-term guidance) in endpoint + UI,
  with rolling-expiry semantics shown in both display and edit form.
- 3 new expiry validation tests; 2 pre-existing message assertions updated.

Full suite 25/25 + race clean via run-tests.sh lockfile; svelte-check 0
errors/warnings; production build succeeds.

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

@@ -2,7 +2,7 @@
 	import { apiFetch } from '$lib/utils/api';
 	import { toast } from 'svelte-sonner';
 	import { extractErrorMessage } from '$lib/utils/toast-safe';
-	import { SvelteDate, SvelteSet, SvelteURLSearchParams } from 'svelte/reactivity';
+	import { SvelteSet, SvelteURLSearchParams } from 'svelte/reactivity';
 	import { CalendarDate, getLocalTimeZone, type DateValue } from '@internationalized/date';
 	import { isValidUKPhone, toE164UK } from '$lib/utils/phone';
 	import { formatUserName } from '$lib/utils/nameDisplay';
@@ -217,7 +217,7 @@
 	// Date Boundaries
 	const today = getLondonTodayCalendarDate();
 	const minDate = today;
-	const maxDate = new SvelteDate(today.year, today.month - 1, today.day);
+	const maxDate = new Date(today.year, today.month - 1, today.day);
 	maxDate.setMonth(today.month - 1 + 6);
 	const maxCalendarDate = new CalendarDate(
 		maxDate.getFullYear(),
@@ -397,8 +397,8 @@
 			!bookingCreateAutoSelectDone
 		) {
 			bookingCreateAutoSelectDone = true;
-			const now = new SvelteDate(getLondonTodayCalendarDate().toString() + 'T00:00:00');
-			const maxDateJs = new SvelteDate(
+			const now = new Date(getLondonTodayCalendarDate().toString() + 'T00:00:00');
+			const maxDateJs = new Date(
 				maxCalendarDate.year,
 				maxCalendarDate.month - 1,
 				maxCalendarDate.day
@@ -408,7 +408,7 @@
 			);
 			const daysToCheck = Math.min(daysDifference, 180);
 			for (let i = 0; i <= daysToCheck; i++) {
-				const checkDate = new SvelteDate(now);
+				const checkDate = new Date(now);
 				checkDate.setDate(now.getDate() + i);
 				const dateStr = checkDate.toLocaleDateString('en-CA', { timeZone: 'Europe/London' });
 				const calDate = new CalendarDate(
@@ -757,7 +757,7 @@
 				return;
 			}
 
-			const now = new SvelteDate();
+			const now = new Date();
 			const diff = reservationExpiresAt.getTime() - now.getTime();
 
 			if (diff <= 0) {