feat(links): move friend links to native WordPress links with review flow

- enable the native Links manager and drop the custom friend-link option/REST path
- add per-page link settings for the friends template
- render link categories from get_bookmarks() with search and page-content options
- add a validated public link submission endpoint with logo upload, captcha, rate limiting and duplicate checks
- create pending links for review and notify administrators by email and in-app message
- add native Links admin pending count, columns and edit notes
- cover the new submission and cleanup contracts

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/Admin/Schema/SchemaPermissions.php

@@ -83,6 +83,7 @@ class SchemaPermissions {
                                 ['label' => '打赏用户', 'value' => 'tip_user'],
                                 ['label' => '提交工单', 'value' => 'ticket_create'],
                                 ['label' => '回复工单', 'value' => 'ticket_reply'],
+                                ['label' => '友情链接申请', 'value' => 'friend_link'],
                             ]],
                         ]],
                         ['key' => 'providers', 'title' => '服务商配置', 'dependsOn' => ['key' => 'enabled', 'value' => true], 'fields' => $provider_fields],