Roadmap blockers — moved

Consolidated into docs/PLAN.md §2.

Roadmap — what we can’t build right now

Absorbed into the master plan §2 (“SKIPPED” — the 🚧 blocked subsections). Hardware / upstream-library / budget blockers all live there. The Phase 9 / 10 status appendix that used to live here is now distributed across §1 (shipped) and §2 (blocked).