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.

backend/handlers/admin/settings.go

@@ -169,8 +169,12 @@ func UpdateBusinessSettings(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "voucher_type must be 'SPV' or 'MPV'", http.StatusBadRequest)
 		return
 	}
-	if req.GiftCardExpiryMonths != nil && *req.GiftCardExpiryMonths < 1 {
-		http.Error(w, "gift_card_expiry_months must be at least 1", http.StatusBadRequest)
+	if req.GiftCardExpiryMonths != nil && *req.GiftCardExpiryMonths < 12 {
+		// Legal floor, not arbitrary: UK Consumer Rights Act 2015 requires
+		// expiry terms to be "fair and transparent", and CMA guidance flags
+		// sub-12-month expiry windows as at risk of being an unfair contract
+		// term. 24 months is the documented default (matches John Lewis, M&S).
+		http.Error(w, "gift_card_expiry_months must be at least 12 (CMA guidance flags sub-12-month expiry as an unfair contract term; 24 is recommended)", http.StatusBadRequest)
 		return
 	}
 	if req.DefaultVATRate != nil && (*req.DefaultVATRate < 0 || *req.DefaultVATRate > 100) {

backend/handlers/admin/settings_test.go

@@ -725,6 +725,65 @@ func TestUpdateBusinessSettings_VoucherType_SPV(t *testing.T) {
 	}
 }
 
+// TestUpdateBusinessSettings_Expiry_RejectsSub12 rejects gift_card_expiry_months
+// below the legal floor. The setting now actually drives gift-card expiry (the
+// cleanup job + every expiry_date write), so a sub-12-month window — flagged by
+// CMA guidance as an unfair contract term under the Consumer Rights Act 2015 —
+// must not be settable.
+func TestUpdateBusinessSettings_Expiry_RejectsSub12(t *testing.T) {
+	ctx, _ := testutils.SetupTestTx(t)
+
+	handler := http.HandlerFunc(UpdateBusinessSettings)
+	body := UpdateBusinessSettingsRequest{
+		GiftCardExpiryMonths: intPtr(6),
+	}
+	w := makeAdminRequest(handler, "PUT", "/api/admin/settings", body, ctx)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected status 400 for 6-month expiry, got %d. body: %s", w.Code, w.Body.String())
+	}
+}
+
+// TestUpdateBusinessSettings_Expiry_RejectsZero rejects gift_card_expiry_months
+// of 0 (previously the only invalid value, now the legal floor subsumes it).
+func TestUpdateBusinessSettings_Expiry_RejectsZero(t *testing.T) {
+	ctx, _ := testutils.SetupTestTx(t)
+
+	handler := http.HandlerFunc(UpdateBusinessSettings)
+	body := UpdateBusinessSettingsRequest{
+		GiftCardExpiryMonths: intPtr(0),
+	}
+	w := makeAdminRequest(handler, "PUT", "/api/admin/settings", body, ctx)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected status 400 for 0-month expiry, got %d. body: %s", w.Code, w.Body.String())
+	}
+}
+
+// TestUpdateBusinessSettings_Expiry_Accepts24 verifies a 24-month window (the
+// documented default) is accepted and persisted.
+func TestUpdateBusinessSettings_Expiry_Accepts24(t *testing.T) {
+	ctx, _ := testutils.SetupTestTx(t)
+
+	handler := http.HandlerFunc(UpdateBusinessSettings)
+	body := UpdateBusinessSettingsRequest{
+		GiftCardExpiryMonths: intPtr(24),
+	}
+	w := makeAdminRequest(handler, "PUT", "/api/admin/settings", body, ctx)
+
+	if w.Code != http.StatusOK {
+		t.Errorf("expected status 200 for 24-month expiry, got %d. body: %s", w.Code, w.Body.String())
+	}
+
+	var s BusinessSettings
+	if err := parseResponseBody(w, &s); err != nil {
+		t.Fatalf("failed to parse response: %v", err)
+	}
+	if s.GiftCardExpiryMonths != 24 {
+		t.Errorf("expected GiftCardExpiryMonths 24, got %d", s.GiftCardExpiryMonths)
+	}
+}
+
 // TestUpdateBusinessSettings_VoucherType_MPV accepts MPV.
 func TestUpdateBusinessSettings_VoucherType_MPV(t *testing.T) {
 	ctx, _ := testutils.SetupTestTx(t)
@@ -764,7 +823,7 @@ func TestUpdateBusinessSettings_NegativeExpiryMonths(t *testing.T) {
 	if w.Code != http.StatusBadRequest {
 		t.Errorf("expected status 400, got %d. body: %s", w.Code, w.Body.String())
 	}
-	if w.Body.String() != "gift_card_expiry_months must be at least 1\n" {
+	if !strings.Contains(w.Body.String(), "must be at least 12") {
 		t.Errorf("unexpected error message: %s", w.Body.String())
 	}
 }
@@ -782,8 +841,8 @@ func TestUpdateBusinessSettings_ExpiryMonths_Negative(t *testing.T) {
 	if w.Code != http.StatusBadRequest {
 		t.Errorf("expected status 400 for negative expiry, got %d. body: %s", w.Code, w.Body.String())
 	}
-	if w.Body.String() != "gift_card_expiry_months must be at least 1\n" {
-		t.Errorf("unexpected error message: %s", w.Body.String())
+	if !strings.Contains(w.Body.String(), "must be at least 12") {
+		t.Errorf("expected legal-floor error message, got: %s", w.Body.String())
 	}
 }