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>

inc/modules/captcha.php

@@ -377,6 +377,7 @@ function jio_captcha_scenes(): array {
 		'tip_user'          => __('打赏用户', 'jio'),
 		'ticket_create'     => __('提交工单', 'jio'),
 		'ticket_reply'      => __('回复工单', 'jio'),
+		'friend_link'       => __('友情链接申请', 'jio'),
 	];
 }