[M6] Implement refresh-context recovery policy

## Why
Needed for retrieval/memory staleness recoveries.

## Scope
- Clear/refetch context; replan pending actions
- Wire into `suggest_recovery_actions` for retrieval/memory

## Acceptance criteria
- [ ] Action + policy
- [ ] Tests on a stale-retrieval or stale-memory case

## References
- Roadmap: `docs/roadmap.md`
- Related vertical slice: `experiments/results/tool-semantic-drift-001.md`
