chore(beads): update .gitignore and config.yaml

- Add sync state files to .gitignore (.sync.lock, sync_base.jsonl)
- Add types.custom to config.yaml for Gas Town type fallback
- Remove metadata.json from .gitignore (it should be tracked)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Executed-By: mayor
Role: mayor

.beads/config.yaml

@@ -51,4 +51,6 @@ sync-branch: "beads-metadata"
 # - linear.url
 # - linear.api-key
 # - github.org
-# - github.repo
+# - github.repo
+# Custom issue types for Gas Town (fallback when database is unavailable)
+types.custom: "agent,role,rig,convoy,slot,queue,event,message,molecule,gate,merge-request"