Add Gas Town files to gitignore

Author: furiosa

.gitignore

@@ -10,4 +10,7 @@ __pycache__/
 **/.DS_Store
 e2e/facilitators/external-proxies/*
 !e2e/facilitators/external-proxies/README.md
-typescript/package-lock.json
+typescript/package-lock.json
+# Gas Town infrastructure
+.beads/
+AGENTS.md