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.

image-hosts.config.js

@@ -17,11 +17,11 @@ export const imageHosts = [
     },
     {
         protocol: 'https',
-        hostname: 'img.rocket.new',
+        hostname: '*.supabase.co',
     },
     {
         protocol: 'https',
-        hostname: '*.supabase.co',
+        hostname: 'supabase.onsethost.com',
     },
     {
         protocol: 'https',