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>

tests/widget-system/frontend-avatar-shape-contract.test.cjs

@@ -53,11 +53,11 @@ test('the user center and public user home keep their legacy rounded-square avat
   assert.doesNotMatch(userHome, /\.jio-author-hero__avatar img\s*\{[^}]*--radius-avatar/s);
 });
 
-test('every other frontend avatar frame is circular', () => {
-  const friends = read('assets/css/routes/friends.css');
+test('link page cards keep their circular logo frames', () => {
+  const links = read('assets/css/routes/links.css');
 
-  assert.match(friends, /\.friend-card__avatar\s*\{[^}]*border-radius:\s*var\(--radius-avatar,\s*50%\)/s);
-  assert.doesNotMatch(friends, /\.friend-card__avatar\s*\{[^}]*border-radius:\s*var\(--radius\)/s);
+  assert.match(links, /\.links-card\.big-card \.link-img img\s*\{[^}]*border-radius:\s*100px/s);
+  assert.match(links, /\.link-img\s*\{[^}]*width:\s*var\(--this-size\)/s);
 });
 
 test('the user card name row can shrink once the VIP icon joins the badge row', () => {