feat(vip): skeleton loading state and faster modal/site startup

The VIP purchase/renew modal opened with a single "loading..." line, which
reads as a hang while /pay/vip/modal round-trips. Every frontend pageview
also paid an option write inside wp_head, and the header user-card CSS was
enqueued even for guests who never see the card.

pay-vip.js now builds a full-layout skeleton (user box, level tabs, the
two-column package panel) from vipSkeleton(), reusing the global
aksrt-modal-runtime__skeleton line/block classes; the VIP-specific shapes
live in the conditionally loaded vip-modal.css, and the 640px two-column
threshold matches .pay-vip-form-row. The modal cache TTL goes 15s -> 60s
(purchase, card-pass redeem and points exchange already invalidate the
vip tag), and hover/focus on a .pay-vip trigger now prefetches the payload
through the same cacheKey and flight openRemote uses, so a warm click
opens instantly.

The bottom note and the whole help_text pipeline behind it are removed; the
admin-editable pay_user_vip_desc still renders at the top of the modal, and
the recharge/gateway help_text keys are untouched. get_catalog() reads
points and wallet balance through one new LedgerService::points_and_balance()
call. The StatsTracker counter write moves to shutdown so wp_head only does
the visitor check and setcookie, and header-userbox.css is enqueued for
logged-in users only.

Verification: node --test across the suite (628 tests, including the 7 new
contract assertions in tests/widget-system/vip-modal-skeleton.test.cjs) and
php -l on every changed PHP file. No visual acceptance performed, per request.

src/Content/VipServiceModal.php

@@ -115,7 +115,6 @@ trait VipServiceModal {
             'prefer_level' => $prefer_level,
             'catalog' => [
                 'desc' => (string) ($catalog['desc'] ?? ''),
-                'help_text' => (string) ($catalog['help_text'] ?? ''),
                 'more' => (string) ($vip['more'] ?? ''),
                 'currency_name' => (string) ($catalog['currency_name'] ?? ''),
                 'level_packages' => $groups,

src/Content/VipServicePurchase.php

@@ -232,21 +232,19 @@ trait VipServicePurchase {
             }
         }
 
-		$points_balance = $user_id > 0 ? \AKSRT\Ledger\LedgerService::get_instance()->balance($user_id, \AKSRT\Ledger\AssetType::POINTS) : 0;
-		$wallet_balance = $user_id > 0 ? \AKSRT\Ledger\LedgerService::get_instance()->balance_decimal($user_id) : '0.00';
+		$balances = \AKSRT\Ledger\LedgerService::get_instance()->points_and_balance($user_id);
         $methods = $this->available_payment_methods();
         $currency_name = class_exists('\AKSRT\Settings\Settings') ? \AKSRT\Settings\Settings::get_currency_name() : __('积分', 'aksrt');
 
         $catalog = [
             'enabled'            => !empty($vip['enabled']),
             'desc'               => (string) ($vip['desc'] ?? ''),
-            'help_text'          => (string) ($vip['help_text'] ?? ''),
             'user_level'         => $level,
             'user_expires'       => $expires,
             'user_is_permanent'  => $is_permanent,
             'user_expires_label' => (string) ($member['expires_label'] ?? ''),
-            'user_points'        => $points_balance,
-            'wallet_balance'     => $wallet_balance,
+            'user_points'        => $balances['points'],
+            'wallet_balance'     => $balances['balance'],
             'currency_name'      => $currency_name,
             'renew_enabled'      => $renew_enabled,
             'upgrade_enabled'    => $upgrade_enabled,