docs(plan): mark Phase 10 complete; note Alt+Arrow follow-up

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: edeno

.claude/docs/plans/v3-workspace-cutover/PLAN.md

@@ -1,6 +1,6 @@
 # v3.0.0 Workspace Cutover — Implementation Plan
 
-**Status:** Phases 0–9 complete (merged to `modern`). Phase 10 next.
+**Status:** Phases 0–10 complete (merged to `modern`). Phase 11 (cutover) next.
 
 Carries the `modern` branch from its mid-build state (M8a complete; new multi-page workspace exists
 but cannot export YAML and loses data on refresh) through to **v3.0.0**, where the workspace UI is a