feat(user-center): add cash wallet balance separate from credits

Introduce AKSRT_Balance (user_meta aksrt_balance + balance_log) for
Zibll-like pay_balance wallet. User center assets panel shows wallet
and points; balance gateway/card-pass/refunds credit cash when enabled.

inc/helpers/aksrt-user-center.php

@@ -432,6 +432,8 @@ if (!function_exists('aksrt_get_user_center_render_context')) {
 		$affiliate_settings = class_exists('AKSRT_Settings') ? AKSRT_Settings::get_payment_affiliate_settings() : [];
 		$show_credit_tabs = (bool) ($dashboard['credits_enabled'] ?? false);
 		$currency_name = (string) ($dashboard['currency_name'] ?? __('积分', 'aksrt'));
+		$balance_enabled = (bool) ($dashboard['balance_enabled'] ?? false);
+		$wallet_balance = (float) ($dashboard['wallet_balance'] ?? 0.0);
 
 		$render_context = [
 			'user_center_settings'      => $user_center_settings,
@@ -470,6 +472,8 @@ if (!function_exists('aksrt_get_user_center_render_context')) {
 			'currency_name'             => $currency_name,
 			'credit_balance'            => (float) ($dashboard['credit_balance'] ?? 0.0),
 			'credits_enabled'           => $show_credit_tabs,
+			'balance_enabled'           => $balance_enabled,
+			'wallet_balance'            => $wallet_balance,
 			'vip_settings'              => $vip_settings,
 			'show_invite_section'       => $show_credit_tabs
 				&& class_exists('AKSRT_Settings')