778b39d3b5
Add agent_config_revisions table for tracking agent configuration changes with rollback support. Add issue_approvals junction table linking issues to approvals. New migrations (0005, 0006) for permissions column and new tables. Rework migration client with statement-level idempotency checks (table/column/index/constraint existence) so migrations can be safely retried against partially-migrated databases. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>