Extracted the helpers we use (JID parsing, trigger mapping, channel
auth registry, generateId, v2PlatformId) into setup/migrate-v2/shared.ts.
Deleted setup/migrate-v1/ entirely — no code references it anymore.
Updated README, CLAUDE.md, docs/v1-to-v2-changes.md, and
docs/migration-dev.md to reference the new paths and migrate-v2.sh
entry point.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
