fix(ai-disclosure): remove every visible "AI persona" reference + team-card visibility

Two unrelated production bugs called out in the same review pass:

1) AI persona disclosure — strictly removed everywhere readers see it.
   - /about/team hero subtitle no longer says "trained AI personas working
     under house style"; copy now reads like every other newsroom team page.
   - /about "How we work" block drops the line about AI assistants
     rewriting press releases + the "Our AI personas are clearly labeled"
     sentence. Reworded to just describe the editorial process.
   - ArticleComments no longer renders the small "AI" chip beside
     is_ai_seeded commenters. The flag stays in the DB for internal
     accounting; it just doesn't surface in the UI.
   - Stale code comments in articles/[slug] + news/[slug] that referenced
     "AI personas participate (tagged)" cleaned up.
   The is_ai_seeded / is_ai_response columns are now strictly internal-only.

2) Team page card visibility — the page wrapper got switched from
   text-[#e5e7eb] to text-[#0F172A] in the recent restyle, which fixed
   white-on-white outside the cards but left the dark-card H3 names
   inheriting dark navy on a dark navy bg = invisible. Forced text-white
   on both H3s (editorial + ops). Email rows now use min-w-0 + flex-1 +
   block truncate so long addresses ellipsis inside the card instead of
   pushing the layout past the right edge.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/articles/[slug]/ArticleDetailClient.tsx

@@ -389,7 +389,7 @@ export default function ArticleDetailClient({ article, relatedArticles, relatedF
             </div>
 
             {/* Article comments — anonymous read, signed-in members can
-                post + vote + reply. AI personas participate too (tagged). */}
+                post + vote + reply. */}
             <ArticleComments articleSlug={article.slug} />
           </div>