Rewrite plan-mode deep dive as implementation blueprint

- Reframe doc into a provider-agnostic implementation plan for Codex, Claude, and Cursor
- Define canonical mode, plan, and structured user-input models plus capability-driven UI behavior
- Add concrete orchestration, adapter, frontend, and test work items for rollout
ed2c4bd856Julius Marminge committed on 3/6/2026, 2:13:20 AMparentb5d5b39
1 file changedLine totals unavailable