fix(setup): isolate scratch agent with hardcoded _ping-test folder

- Scratch agent uses fixed folder `_ping-test` so it can never collide
  with a real agent on re-runs
- Added --folder flag to init-cli-agent.ts and cli-agent step wrapper
- Delete always targets `_ping-test` exactly — no re-derivation needed
- Removed normalizeName coupling and FOLDER status field (no longer needed)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/delete-cli-agent.ts

@@ -1,9 +1,10 @@
 /**
  * Delete the scratch CLI agent created during setup's ping-pong test.
  *
- * Removes the agent group, its messaging_group_agents wiring, any
- * agent_destinations rows, and the groups/<folder>/ directory. Leaves the
- * CLI messaging group intact so it can be reused for a new agent.
+ * Dynamically finds and removes all rows referencing the agent group
+ * (any table with an agent_group_id column), deletes the agent group
+ * itself, and removes the groups/<folder>/ directory. Leaves the CLI
+ * messaging group intact so it can be reused for a new agent.
  *
  * Usage:
  *   pnpm exec tsx scripts/delete-cli-agent.ts --folder <folder-name>