docs: remove completed PR #3316 review notes

- Delete docs/dev-notes/2026-03-26/pr-3316-review/plan.md (implementation complete)
- Delete docs/dev-notes/2026-03-26/pr-3316-review/review.md (no longer needed)
- All findings have been addressed and committed

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: KATO-Hiro