Add roadmap finalization task audit

docs/modernization/roadmap.md

@@ -1,7 +1,7 @@
 # PanoPainter Modernization Roadmap
 
 Status: live
-Last updated: 2026-06-13
+Last updated: 2026-06-14
 
 This is the living roadmap for modernizing PanoPainter into independently
 testable C++23 components while retaining all existing functionality. Keep this
@@ -62,6 +62,13 @@ queue, blocked queue, validation commands, and completion rules. Do not move the
 percentage for a narrowed adapter or added planner unless a task in that file is
 marked `Done` with validation and a debt/roadmap update.
 
+The 2026-06-14 planning audit added measurable blockers for roadmap
+finalization: component boundary self-tests (`ARCH-001`), renderer backend
+contract freeze and conformance (`RND-007`, `RND-008`), opt-in Vulkan/Metal lab
+targets (`RND-009`, `RND-010`), UI thread-affinity and checked-handle migration
+(`UI-001`, `UI-002`), render/UI queue race coverage (`APP-001`), package gates
+for backend/UI work (`PLT-010`), and historical task cleanup (`AUD-001`).
+
 Recent 2026-06-13 retained preview reductions continue to narrow DEBT-0036:
 `NodeStrokePreview::draw_stroke_immediate()` now also routes
 feedback/material/composite planning and stroke-shader uniform assembly through
@@ -1829,6 +1836,11 @@ Gate:
 
 Goal: prepare Vulkan and Metal without destabilizing the OpenGL parity path.
 
+Status: not started. Do not start production Vulkan or Metal work until
+`RND-007` and `RND-008` freeze and validate the renderer API backend contract.
+`RND-009` and `RND-010` are opt-in lab targets only and must stay outside the
+production app path.
+
 Implementation tasks:
 
 - Create non-default targets only after OpenGL backend parity: