fix(user-center): drop expiry row from unopened VIP status card

The status card always rendered the expiry row, so never-opened members saw a redundant 到期时间：未开通 line under the 未开通 state label. The reference theme outputs no expiry info for never-opened users (only active, permanent, and expired states carry one).

Initialize the expiry text empty and render the row only when the text is non-empty; active/permanent/expired branches are unchanged.

Verification: new tests/widget-system/vip-tab-status-card.test.cjs (2 contract tests); node --test tests/**/*.test.cjs 637/637 pass; php -l clean.

inc/helpers/user-center-renderers/vip-tab.php

@@ -36,7 +36,9 @@ $vip_state_label    = __('未开通', 'aksrt');
 $vip_level_number   = 0;
 $vip_level_name     = __('未开通会员', 'aksrt');
 $vip_description    = $desc_top !== '' ? $desc_top : __('开通会员，尊享专属特权', 'aksrt');
-$vip_expiry_text    = __('到期时间：未开通', 'aksrt');
+// 未开通时不留到期文案：状态标签已显示「未开通」，参考主题对从未开通
+// 用户同样不输出任何到期信息（仅生效中/永久/已过期才有）。
+$vip_expiry_text    = '';
 $vip_is_permanent   = false;
 $btn_type           = 'pay';
 
@@ -95,7 +97,7 @@ $status_html = '<div class="uc-vip-status" role="status">'
 	. '<span class="uc-vip-status__level">' . esc_html($vip_level_name) . '</span>'
 	. '</div>'
 	. '<div class="uc-vip-status__desc">' . esc_html($vip_description) . '</div>'
-	. '<div class="uc-vip-status__expiry"><i class="fa fas fa-clock" aria-hidden="true"></i><span>' . esc_html($vip_expiry_text) . '</span></div>'
+	. ($vip_expiry_text !== '' ? '<div class="uc-vip-status__expiry"><i class="fa fas fa-clock" aria-hidden="true"></i><span>' . esc_html($vip_expiry_text) . '</span></div>' : '')
 	. '</div>';
 
 // Level cards.