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-article-notification/index.ts

@@ -34,7 +34,7 @@ serve(async (req) => {
       throw new Error("RESEND_API_KEY is not set");
     }
 
-    const siteUrl = "https://broadcastb5322.builtwithrocket.new";
+    const siteUrl = "https://broadcastbeat.com";
     const articleUrl = article.slug
       ? `${siteUrl}/articles/${article.slug}`
       : article.wp_slug