Implement full Square payment review fixes + frontend polish

Implement every finding from the deep payment review (P0-P2, minors,
nitpicks), then close the post-implementation re-review items, then
align card-form typography and roll out the Square trust badge.

Backend - Square API alignment:
- tip_settings.allow_tipping nested under device_options (was top-level:
  terminal tips were silently lost in prod)
- CreateCardOnFile now accepts customerID and sends card.customer_id;
  saved-card (ccof:) charges forward square_customer_id as CustomerID
- New SquareClient methods GetPayment, CreateCustomer, CancelCheckout
- SCA verification_token accepted + forwarded in all charge paths
- ExpMonth/ExpYear -> *int; URL-path id validation; CancelCheckout
  NOT_FOUND-only no-op (dropped unverified NOOP); exported ErrorCode/
  ErrorDetail helpers; mock rejects raw PANs, RList locks, redacts
  emails, ForceRefundPending hook

Backend - money safety:
- sweepManualPendingSquareRefunds reconciles rows WITH square_refund_id
  instead of stranding them forever
- SweepStalePendingPayments reconciles at Square before failing (tri-state:
  leave pending on transport error, rescue completed, fail definitively)
- GetCheckoutStatus cancellation-recheck; terminal CANCELED resolution;
  SweepStaleTerminalCheckouts covers terminal_checkouts table
- till gift-card clawback on definitive failure incl. retry path +
  INSUFFICIENT_FUNDS/ADDRESS_VERIFICATION_FAILURE/TRANSACTION_LIMIT
- cross-user saved-card collision fixed (UNIQUE(user_id,square_card_id))
- customer provisioning (lazy, save-only); one-off/guest mint no customer
- discount preview/apply unified in discounts.go (global-milestone visible
  in preview, N+1 eliminated, redemption counter preserved on failures)
- webhook event_id dedup; refund loop dedup; stale comment fixes
- test-isolation t.Cleanup on committed sweep tests

Frontend:
- SCA tokenizeWithVerification across all charge flows (amount as
  major-units decimal), 5-min token-expiry re-tokenize, verification_token
  in request bodies
- PaymentModal synchronous double-click + zero/negative-amount guards
- till online-card UI wired to /api/admin/till/sale
- policyPopover generalised; new /privacy-policy route; consent checkbox
  copy + Square privacy link
- Square card iframe styled to app typography (Inter 14px, oklch tokens);
  mock form md:text-sm parity
- 'Secure payment powered by Square' badge on all 8 card-payment flows

Schema/docs: terminal_checkouts + square_customer_id + per-user card
constraint in init-script.sql; README migrations; P14 plan + backlog +
Technical Manual updated.

Includes 39 modified/new test files; full backend suite (25 pkgs),
-race on payments+square, and frontend build are green.

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

@@ -610,15 +610,27 @@
 		onlineSquareProcessing = true;
 		paymentError = '';
 		try {
+			const amt = actionType === 'create' ? Number(generateAmount) : Number(topUpAmount);
 			let token: string;
+			let verificationToken: string | null;
 			try {
-				token = await onlineSquareCardInput.tokenize();
+				const contact = selectedCustomer
+					? {
+							givenName: selectedCustomer.name?.split(' ')[0],
+							email: selectedCustomer.email
+						}
+					: undefined;
+				const tokenized = await onlineSquareCardInput.tokenizeWithVerification(
+					Math.round(amt * 100),
+					contact
+				);
+				token = tokenized.nonce;
+				verificationToken = tokenized.verificationToken;
 			} catch (err) {
 				paymentError = err instanceof Error ? err.message : 'Card entry failed';
 				setModalStep(actionType, 'error');
 				return;
 			}
-			const amt = actionType === 'create' ? Number(generateAmount) : Number(topUpAmount);
 			const body: Record<string, unknown> = {
 				item_type: 'gift_card',
 				action: actionType,
@@ -627,6 +639,7 @@
 				card_token: token,
 				idempotency_key: getIdempotencyKey()
 			};
+			if (verificationToken) body.verification_token = verificationToken;
 			if (gcId) body.gift_card_id = gcId;
 			if (selectedCustomer) body.user_id = selectedCustomer.id;
 			if (actionType === 'create' && generateType === 'account' && selectedCustomer)
@@ -1909,6 +1922,7 @@
 						>
 							{onlineSquareProcessing ? 'Processing...' : 'Pay by Card'}
 						</Button>
+						<p class="mt-4 text-center text-xs text-gray-500">Secure payment powered by Square</p>
 					</div>
 				{/if}
 			</div>
@@ -2181,6 +2195,7 @@
 						>
 							{onlineSquareProcessing ? 'Processing...' : 'Pay by Card'}
 						</Button>
+						<p class="mt-4 text-center text-xs text-gray-500">Secure payment powered by Square</p>
 					</div>
 				{/if}
 			</div>