feat: add migrate-v2.sh — standalone v1 → v2 migration script

New entry point: `bash migrate-v2.sh` from the v2 checkout.
Replaces the old setup-embedded migration flow with a standalone
4-phase script + rewritten Claude skill for the interactive parts.

Phase 0: Bootstrap (Node/pnpm/deps via setup.sh) + find v1
Phase 1: Core state (env, DB, groups, sessions, tasks)
Phase 2: Channels (clack multiselect, auth copy, code install)
Phase 3: Infrastructure (OneCLI, auth, Docker, skills, container build)
Service switchover: stop v1 → start v2 → test → keep or revert
Phase 4: Handoff → exec claude "/migrate-from-v1"

The skill handles: owner seeding, access policy, CLAUDE.local.md
cleanup, container config validation, fork customization porting.

Key fixes found during testing:
- triggerToEngage: requires_trigger=0 must override non-empty pattern
- unknown_sender_policy defaults to 'public' (strict drops all msgs
  before owner is seeded)
- Service revert must stop v2 (parse unit name from step log, not
  early tsx one-liner that can fail)
- Session continuity: copy JSONL from -workspace-group/ to
  -workspace-agent/ and write continuation:claude into outbound.db
- container_config.additionalMounts written directly to container.json
  (same shape in v1 and v2)
- EXIT trap writes handoff.json; explicit write_handoff before exec

Includes migrate-v2-reset.sh for dev iteration and docs/migration-dev.md
for testing/debugging reference.

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

setup/migrate-v2/select-channels.ts

@@ -0,0 +1,63 @@
+/**
+ * migrate-v2: interactive channel selection via clack multiselect.
+ *
+ * Writes selected channel names (one per line) to the file path given as
+ * the first argument. Clack renders to the terminal normally.
+ *
+ * If NANOCLAW_CHANNELS env var is set (comma-separated names), skips the
+ * prompt and writes those directly.
+ *
+ * Usage: pnpm exec tsx setup/migrate-v2/select-channels.ts <output-file>
+ */
+import fs from 'fs';
+
+import * as p from '@clack/prompts';
+
+const CHANNELS = [
+  { value: 'telegram',       label: 'Telegram' },
+  { value: 'discord',        label: 'Discord' },
+  { value: 'slack',          label: 'Slack' },
+  { value: 'whatsapp',       label: 'WhatsApp' },
+  { value: 'teams',          label: 'Microsoft Teams' },
+  { value: 'matrix',         label: 'Matrix' },
+  { value: 'imessage',       label: 'iMessage' },
+  { value: 'webex',          label: 'Webex' },
+  { value: 'gchat',          label: 'Google Chat' },
+  { value: 'resend',         label: 'Resend (email)' },
+  { value: 'github',         label: 'GitHub' },
+  { value: 'linear',         label: 'Linear' },
+  { value: 'whatsapp-cloud', label: 'WhatsApp Cloud API' },
+];
+
+const VALID_NAMES = new Set(CHANNELS.map((c) => c.value));
+
+async function main(): Promise<void> {
+  const outFile = process.argv[2];
+  if (!outFile) {
+    console.error('Usage: tsx setup/migrate-v2/select-channels.ts <output-file>');
+    process.exit(1);
+  }
+
+  // Non-interactive: NANOCLAW_CHANNELS="telegram,discord"
+  const envChannels = process.env.NANOCLAW_CHANNELS?.trim();
+  if (envChannels) {
+    const names = envChannels.split(',').map((s) => s.trim()).filter((s) => VALID_NAMES.has(s));
+    fs.writeFileSync(outFile, names.join('\n') + '\n');
+    return;
+  }
+
+  const selected = await p.multiselect({
+    message: 'Which channels do you want to set up?',
+    options: CHANNELS,
+    required: false,
+  });
+
+  if (p.isCancel(selected)) {
+    fs.writeFileSync(outFile, '');
+    return;
+  }
+
+  fs.writeFileSync(outFile, (selected as string[]).join('\n') + '\n');
+}
+
+main();