Add auto-merge workflow for agent-sync branch and stop pushing to main

CEO commits memory/runtime updates to agent-sync branch instead of main.
GitHub Actions workflow auto-merges agent-sync into main on push.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ceo/HEARTBEAT.md

@@ -79,8 +79,7 @@ This repo (`/paperclip/privilegedescalation/agents`) is the canonical source of
     cd /paperclip/privilegedescalation/agents
     git add -A
     git diff --cached --quiet || git commit -m "agent: memory and runtime updates $(date -u +%Y-%m-%dT%H:%M:%SZ)"
-    git pull --rebase origin main
-    git push origin main
+    git pull --rebase origin main && git push origin HEAD:refs/heads/agent-sync -f
 
 #### 5b. Detect changes since last sync