Migrate classic Slack agents

Turn every agent group wired through the classic instance='slack' adapter into a named slack-<slug> bot without replacing the agent group. This is an operator-guided, resumable data migration. It never creates an agent group and never edits an agent workspace.

Migration is optional. Classic single-bot Slack remains fully supported; this skill first offers the choice, and staying on classic is a valid outcome that also satisfies the update requirement.

Hard invariants:

• Never call create_agent or ncl groups create.
• Never change an agent_groups.id or write under groups/<folder>/.
• Never merge the channels branch; fetch and copy skill-owned files only.
• Never print token values. Show key names and masked presence only.
• Keep classic rows, credentials, and the shared Slack app available for rollback until the operator explicitly approves cutover.

Phase 1: Detect classic state

Run from the NanoClaw project root. Read the central DB only through the sanctioned wrapper.

Classic state requires all four signals:

1. src/channels/index.ts contains the Slack barrel import import './slack.js';.

2. .env has a non-empty unsuffixed SLACK_BOT_TOKEN and either a non-empty SLACK_APP_TOKEN or SLACK_SIGNING_SECRET. Check presence without echoing values.

3. This query returns at least one row:

   pnpm exec tsx scripts/q.ts data/v2.db "SELECT mg.id, mga.id, mga.agent_group_id FROM messaging_groups mg JOIN messaging_group_agents mga ON mga.messaging_group_id=mg.id WHERE mg.channel_type='slack' AND mg.instance='slack' ORDER BY mg.id, mga.agent_group_id"
   

4. At least one wired group does not yet have complete named-instance coverage: a stable slug, both SLACK_BOT_TOKEN_<SUFFIX> and SLACK_APP_TOKEN_<SUFFIX>, that slug in SLACK_INSTANCES, and the expected slack-<slug> messaging-group/wiring rows.