- Add `agentic.plan_retention_days` config (default 90 days via AGENTIC_PLAN_RETENTION_DAYS env)
- Add SoftDeletes and `archived_at` timestamp to AgentPlan model
- Add migration for `deleted_at` and `archived_at` columns on agent_plans
- Create `agentic:plan-cleanup` command with --dry-run and --days options
- Schedule retention cleanup to run daily via service provider
- Register PlanRetentionCommand in ConsoleBooting handler
- Add PlanRetentionTest feature test suite covering all retention scenarios
- Fix archive() to store archived_at as dedicated column (not metadata string)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
