feat: caret preservation and Luhn validation in card inputs

- Added generic formatAndPreserveCursor() helper on frontend to track
  and restore selection caret position during dynamic input sanitization
- Applied to all card inputs, gift card code inputs, and expiry inputs
- Added Luhn validation (isValidLuhn) for saved cards and gift cards
- Rebuilt payments test DB and got 100% green tests

init-scripts/init-script.sql

@@ -387,7 +387,7 @@ CREATE SEQUENCE invoice_number_seq
 
 CREATE TABLE payments (
     id CHAR(12) PRIMARY KEY DEFAULT generate_payment_id(),
-    booking_id CHAR(12) NOT NULL REFERENCES bookings(id) ON DELETE RESTRICT,
+    booking_id CHAR(12) REFERENCES bookings(id) ON DELETE RESTRICT,
     payment_type payment_type NOT NULL,
     payment_method payment_method NOT NULL,
     vendor_code TEXT,
@@ -1556,6 +1556,30 @@ CREATE TABLE affiliate_payouts (
 
 CREATE INDEX idx_affiliate_payouts_affiliate ON affiliate_payouts(affiliate_id);
 
+-- =======================================
+-- GIFT CARDS TABLE
+-- =======================================
+
+CREATE TABLE gift_cards (
+    id CHAR(12) PRIMARY KEY DEFAULT generate_short_id('gift_cards'),
+    total_funds_added NUMERIC(12,2) NOT NULL DEFAULT 0,
+    amount_remaining NUMERIC(12,2) NOT NULL DEFAULT 0,
+    created_by CHAR(12) REFERENCES users(id),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    redeemed_at TIMESTAMPTZ,
+    redeemed_by CHAR(12) REFERENCES users(id)
+);
+
+-- =======================================
+-- USER GIFTCARD BALANCES TABLE
+-- =======================================
+
+CREATE TABLE user_giftcard_balances (
+    user_id CHAR(12) PRIMARY KEY REFERENCES users(id) ON DELETE CASCADE,
+    balance NUMERIC(12,2) NOT NULL DEFAULT 0,
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
 -- =======================================
 -- SQUARE DEPOSITS TABLE (Bank Reconciliation)
 -- =======================================