chore: purge all rocket.new references from source

- Replace img.rocket.new mock URLs in authors/[slug] + FeaturedBento
  with /assets/images/article-placeholder.svg (live DB data drives
  these pages now; the static maps are fallback only).
- Replace broadcastb5322.builtwithrocket.new with broadcastbeat.com
  in admin API routes, news detail, forum layout, and the 4 Supabase
  edge functions that build outbound email links.
- Swap rocket-hosted JSON-LD logo URL in root layout for the local
  /assets/images/logo.png we already ship.
- Drop img.rocket.new from the Next.js image-hosts allowlist;
  add supabase.onsethost.com so storage proxy URLs can render.

The DB has had zero rocket.new image refs for weeks; this finishes
the job in the codebase so no page on broadcastbeat.com can render
a rocket-hosted asset anymore.

supabase/functions/send-newsletter-confirmation/index.ts

@@ -65,7 +65,7 @@ serve(async (req) => {
               <p style="margin:0 0 8px;font-size:12px;font-weight:700;letter-spacing:0.06em;text-transform:uppercase;color:#888;">Your selected topics:</p>
               ${topicsList}
               <div style="margin:28px 0;border-top:1px solid #2a2a2a;"></div>
-              <a href="https://broadcastb5322.builtwithrocket.new/home-page" style="display:inline-block;background-color:#cc0000;color:#ffffff;font-size:13px;font-weight:700;letter-spacing:0.04em;text-transform:uppercase;text-decoration:none;padding:10px 24px;border-radius:2px;">
+              <a href="https://broadcastbeat.com/home-page" style="display:inline-block;background-color:#cc0000;color:#ffffff;font-size:13px;font-weight:700;letter-spacing:0.04em;text-transform:uppercase;text-decoration:none;padding:10px 24px;border-radius:2px;">
                 Read Latest News →
               </a>
             </td>