M2: mark AI planning coach milestone done

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -23,8 +23,14 @@ go test ./...
 
 ## Status
 
+M2 (AI planning coach): in the Planning view, a rough intent is "sharpened"
+into a structured commitment (next action, success condition, timebox) by an
+LLM CLI backend (claude or codex, selectable via `ANTIDRIFT_AI_BACKEND`). The
+coach runs asynchronously and degrades gracefully — manual planning always
+works.
+
 M1 (evidence & audit): active-window tracking, two-tier evidence store
 (disposable per-session raw log + permanent hash-chained session summaries),
-and live SSE updates. AI integration and drift judgment arrive in later
+and live SSE updates. Live drift judgment and the ambient nudge arrive in later
 milestones (see the roadmap in
 `docs/superpowers/specs/2026-05-31-go-focus-os-design.md`).