fix: loop-B adversarial findings — tip-type double-charge, tip-refund capacity, loyalty stamp farming, gate ordering, auth amplification, admin audit log

Loop B restart (money/security/dup-mod adversarial) fixes:
- CRITICAL: CreateTerminalPayment rejects payment_type='tip' (mirrors CreateBookingPayment) — a tip-typed admin charge no longer records the FULL amount as a tip and double-collects (all is-paid computations exclude tip rows)
- HIGH: tip refunds can no longer re-open booking capacity — refunded_total subqueries filter payment_type <> 'tip' (service.go) and RefundPayment rejects tip rows
- MEDIUM: loyalty-stamp farming closed — stamp award once-per-booking via loyalty_stamp_awarded_at column (init-script.sql) + existing same-day guard
- MEDIUM: CreateTipPayment/CreateBookingPayment 2FA gates moved AFTER the idempotency completed-dedup (code consumed only on new money paths; terminal path already correct) — lost-response retries return the completed payment instead of 400
- MEDIUM: replayRescueLowerBoundSkew widened to 5m (DB-clock-skew stranded originals now rescued)
- MEDIUM-1: verifyFamilyAlive DB amplification reduced via 30s bounded family-alive cache; admin route group rate-limited
- MEDIUM-3: admin saved-card charges now write admin_audit_log (handlers.go helper + till); [2FA] log line decoupled from user identity
- LOW-1: logout scoped to the presented token's family (no cross-session kill)
- LOW-2: refresh-reuse grace widened for same-IP replays
- LOW-4: squareEnvironmentMismatch enforced for empty env
- LOW-5: uuid.ts hard-fails on Math.random fallback (crypto.randomUUID)
- Cash/giftcard tip-enabled overflow mirrors the card-terminal carve

26/26 backend packages; 72/72 frontend tests + build; env-docs 41/41.

frontend/src/lib/utils/uuid.ts

@@ -1,27 +1,17 @@
 /**
- * Generate a UUID v4 string.
+ * Generate a UUID v4 string using `crypto.randomUUID()`.
  *
- * Uses `window.crypto.getRandomValues()` when available (secure context),
- * falls back to `Math.random()` for non-secure contexts (e.g. plain HTTP).
- *
- * Safe for all environments — does NOT rely on `crypto.randomUUID()`
- * which requires a secure context (HTTPS).
+ * The app is HTTPS-only (secure context), so `crypto.randomUUID()` is always
+ * available in the browser and in Node 19+ (vitest/dev server). Idempotency
+ * keys derived here gate Square dedup — they must be unpredictable, so this
+ * HARD-FAILS (throws) rather than silently falling back to `Math.random()` in
+ * a non-secure context (LOW-5). No fallback is ever used.
  */
 export function generateUUID(): string {
-	const array = new Uint8Array(16);
-	if (typeof window !== 'undefined' && window.crypto?.getRandomValues) {
-		window.crypto.getRandomValues(array);
-	} else {
-		for (let i = 0; i < 16; i++) array[i] = Math.floor(Math.random() * 256);
+	if (typeof globalThis.crypto?.randomUUID !== 'function') {
+		throw new Error(
+			'generateUUID requires crypto.randomUUID() (secure context). The app is HTTPS-only; refusing to fall back to Math.random().'
+		);
 	}
-	// UUID v4 marker and variant
-	array[6] = (array[6] & 0x0f) | 0x40;
-	array[8] = (array[8] & 0x3f) | 0x80;
-	return [...array]
-		.map((b, i) => {
-			const hex = b.toString(16).padStart(2, '0');
-			if (i === 4 || i === 6 || i === 8 || i === 10) return '-' + hex;
-			return hex;
-		})
-		.join('');
+	return globalThis.crypto.randomUUID();
 }