docs: restore docs/private/roadmap from 7b4908f9 (Phase 20.31)

docs/private/roadmap/phases/phase-15.78/INDEX.md

@@ -0,0 +1,32 @@
+# Phase 15.78 — Frozen UX Polish, AOT Parity, Legacy Cleanup
+
+Purpose
+- Turn the frozen line into a “useful distribution”: smooth packaging, simple run, light parity checks, and safer legacy retreat.
+
+Tracks
+- A. Distribution & UX
+  - Package dist/ as archives (Linux/Win-gnu/Win-msvc/All-in-one)
+  - release.json enriched (support_matrix, sizes, sha256)
+  - Doctor options: --no-build, --verbose; actionable hints
+  - Quickstart README in archives
+- B. AOT parity & ny_main glue
+  - Simple glue generator (ny_main) via CLI/subcommand or helper script
+  - Light parity smokes (String.len / Array.size / Map.size) VM↔AOT
+- C. Legacy staged retreat
+  - plugin-only profile: legacy-boxes default OFF (quick stays green)
+  - Remove unreachable router arms (warning cleanup)
+  - Track remaining crate::boxes refs and reduce
+- D. Windows final touches
+  - One-command guide for MSVC/MinGW quicklinks
+  - Doctor hints for VS/clang PATH and common pitfalls
+
+DoD
+- dist/pkg/* archives + dist/release.json (support_matrix included)
+- Frozen Quickstart in archives and docs
+- 3–4 light parity smokes pass under VM/AOT (no external I/O)
+- plugin-only profile stays green with legacy-boxes OFF; unreachable code pruned
+- Windows MSVC/MinGW doc paths verified (no missing steps)
+
+Notes
+- Keep existing profiles green. Broader refactors are out of scope; focus on polish and small wins.
+