fix(user-center): remove rebate detail title setting

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/Admin/Schema/SchemaPayment.php

@@ -210,7 +210,6 @@ class SchemaPayment {
                         ]],
                         ['key' => 'text', 'title' => '文案设置', 'fields' => [
                             ['key' => 'pay_rebate_text_desc', 'label' => '返佣说明', 'type' => 'textarea', 'default' => ''],
-                            ['key' => 'pay_rebate_text_details_title', 'label' => '明细标题', 'type' => 'input', 'default' => ''],
                             ['key' => 'pay_rebate_text_details', 'label' => '明细说明', 'type' => 'textarea', 'default' => ''],
                             ['key' => 'pay_rebate_text_discount', 'label' => '折扣文案', 'type' => 'input', 'default' => ''],
                         ]],

src/Settings/PaymentRuntime.php

@@ -287,7 +287,6 @@ class PaymentRuntime {
             ],
             'text'               => [
                 'desc'          => sanitize_textarea_field((string) ($settings['pay_rebate_text_desc'] ?? '')),
-                'details_title' => sanitize_text_field((string) ($settings['pay_rebate_text_details_title'] ?? '')),
                 'details'       => sanitize_textarea_field((string) ($settings['pay_rebate_text_details'] ?? '')),
                 'discount'      => sanitize_text_field((string) ($settings['pay_rebate_text_discount'] ?? '')),
             ],