Wire up wallet balance and gift cards at checkout; fix Square gift card option; fix account/rewards.php CSS; fix real PDO/schema bugs found along the way

Feature: checkout.php now lets logged-in customers apply existing wallet
balance or redeem a gift card code (which tops up wallet first, then
applies) toward their order total. Deduction is deferred to payment
success (markSquarePaymentResult in includes/square.php), never at order
creation, so an abandoned checkout never loses real wallet money - mirrors
how loyalty points already work here, unlike stock which is decremented
eagerly. payment.php gains a second Square Gift Card tab (payments.giftCard()
SDK method) alongside the card form, both hitting the same
create-square-payment.php endpoint since Square treats both source types
identically.

New api/apply-wallet-credit.php validates/quotes an amount without writing
anything - actual spend happens only via markSquarePaymentResult(). The
gift-card-to-wallet transaction logic was extracted out of
api/redeem-gift-card.php into a shared loyalty()->redeemGiftCardToWallet()
so the Wallet page and checkout both call the same code.

Also fixed three unrelated pre-existing bugs surfaced while testing this:
- loyalty.php awardPoints() reused the same named PDO parameter (:points)
  twice in one UPDATE - fails under real prepared statements, meaning
  loyalty points (and the email sent right after them) were silently never
  awarded for any order tied to a logged-in customer.
- redeemGiftCardToWallet (formerly inline in redeem-gift-card.php) referenced
  a gift_cards.updated_at column that does not exist in the schema, and used
  invalid enum values (gift_card_transactions.type=redeem,
  wallet_transactions.type=gift_card) that do not match the actual enum
  definitions - gift card redemption has likely never worked at all.
- account/rewards.php was missing the  line that loads
  account.css, unlike every other account/*.php page, so its sidebar/layout
  rendered unstyled.

includes/loyalty.php

@@ -150,10 +150,10 @@ class LoyaltyProgram {
         db()->query(
             "UPDATE customers SET
                 reward_points = reward_points + :points,
-                lifetime_points = COALESCE(lifetime_points, 0) + :points,
+                lifetime_points = COALESCE(lifetime_points, 0) + :points2,
                 updated_at = NOW()
              WHERE customer_id = :id",
-            ['points' => $totalPoints, 'id' => $customerId]
+            ['points' => $totalPoints, 'points2' => $totalPoints, 'id' => $customerId]
         );
 
         $newBalance = db()->fetch(
@@ -417,6 +417,86 @@ class LoyaltyProgram {
             'new_customer_bonus' => $newCustomerBonus
         ];
     }
+
+    /**
+     * Redeem a gift card code into wallet balance. Shared by the Wallet page
+     * and checkout so both go through the same transaction logic instead of
+     * duplicating it.
+     */
+    public function redeemGiftCardToWallet(string $customerId, string $rawCode): array {
+        $code = strtoupper(str_replace(['-', ' '], '', trim($rawCode)));
+
+        if (empty($code) || strlen($code) < 8) {
+            return ['success' => false, 'error' => 'Invalid gift card code'];
+        }
+
+        $giftCard = db()->fetch(
+            "SELECT * FROM gift_cards WHERE code = :code AND is_active = 1",
+            ['code' => $code]
+        );
+
+        if (!$giftCard) {
+            return ['success' => false, 'error' => 'Gift card not found or already used'];
+        }
+
+        if ($giftCard['current_balance'] <= 0) {
+            return ['success' => false, 'error' => 'This gift card has no remaining balance'];
+        }
+
+        if ($giftCard['expires_at'] && strtotime($giftCard['expires_at']) < time()) {
+            return ['success' => false, 'error' => 'This gift card has expired'];
+        }
+
+        $customer = db()->fetch("SELECT wallet_balance FROM customers WHERE customer_id = :id", ['id' => $customerId]);
+        if (!$customer) {
+            return ['success' => false, 'error' => 'Customer not found'];
+        }
+
+        $amount = $giftCard['current_balance'];
+
+        try {
+            db()->query("START TRANSACTION");
+
+            db()->query(
+                "UPDATE gift_cards SET current_balance = 0, is_active = 0 WHERE gift_card_id = :id",
+                ['id' => $giftCard['gift_card_id']]
+            );
+
+            db()->insert('gift_card_transactions', [
+                'gift_card_id' => $giftCard['gift_card_id'],
+                'amount' => -$amount,
+                'balance_after' => 0,
+                'type' => 'redemption',
+            ]);
+
+            $newWalletBalance = (float) $customer['wallet_balance'] + $amount;
+
+            db()->query(
+                "UPDATE customers SET wallet_balance = :balance, updated_at = NOW() WHERE customer_id = :id",
+                ['balance' => $newWalletBalance, 'id' => $customerId]
+            );
+
+            db()->insert('wallet_transactions', [
+                'transaction_id' => generateId('wt_'),
+                'customer_id' => $customerId,
+                'amount' => $amount,
+                'balance_after' => $newWalletBalance,
+                'type' => 'deposit',
+                'description' => 'Gift card redeemed: ' . $code
+            ]);
+
+            db()->query("COMMIT");
+
+            return [
+                'success' => true,
+                'amount' => $amount,
+                'new_balance' => $newWalletBalance
+            ];
+        } catch (Exception $e) {
+            db()->query("ROLLBACK");
+            return ['success' => false, 'error' => 'Failed to redeem gift card. Please try again.'];
+        }
+    }
 }
 
 // Helper function