av: clone broadcastbeat sources + AV Beat rebrand (Phase 1)

- Replaces the prior Rocket scaffold (saved on pre-bb-clone-rollback branch)
- Domain: broadcastbeat.com -> avbeat.com
- Brand: Broadcast Beat -> AV Beat
- Slug: broadcastbeat -> avbeat (package, identifiers)
- Schema fallback: bb -> av (env var name unchanged)
- Placeholder AV BEAT logo (gold->red gradient) at /assets/logos/av.svg
- All BB/RMP logo references repointed

Outstanding before public DNS swap:
  - Supabase av schema bootstrap (mirror of bb tables)
  - WordPress archive import (avbeat-com -> av.articles)
  - Coolify env vars
  - dev-avbeat.onsethost.com staging deploy + visual review

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://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;">
+              <a href="https://avbeat.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>