Own grid workers and thin Apple platform bridge

docs/modernization/tasks.md

@@ -42,13 +42,15 @@ Completed, blocked, and superseded task history moved to
   `src/node_canvas.cpp`, `src/app.cpp`, and `src/app_dialogs.cpp`.
 - The platform boundary is not finished:
   - `pp_platform_api` still compiles Apple implementation files
-  - Apple platform services still reach `App::I`
-  - Linux FPS title reporting now uses an injected callback, but broader
-    platform-to-app singleton reach is still open
+  - `platform_apple` no longer reaches `App::I` directly, and Linux FPS title
+    reporting now uses an injected callback, but retained Apple bridging and
+    broader platform-to-app singleton reach are still open in
+    `platform_legacy`
   - `platform_legacy` is still part of the live app shell
 - The app runtime boundary is not finished:
   - render/UI queues are static `App` state
-  - detached workers still launch from canvas, grid, preview, and event code
+  - detached workers still launch from canvas, preview, document export, and
+    recording code
   - thread-affinity rules are enforced by convention and asserts instead of
     explicit runtime contracts
 - The UI ownership boundary is not finished:
@@ -125,6 +127,9 @@ Current slice:
 - `NodeStrokePreview` final composite plus preview-texture copy now route
   through `legacy_node_stroke_preview_execution_services.h`, but the preview
   node still owns most live-pass and retained GL resource execution.
+- `NodeCanvas` display resolve for the `m_density != 1.f` path now routes
+  through `legacy_canvas_draw_merge_services.h`, but the cache-to-screen
+  composite block and broader canvas draw orchestration are still inline.
 
 Write scope:
 - `src/node_stroke_preview.cpp`
@@ -348,7 +353,10 @@ Current slice:
   moving behind owned runtime/service objects
 - brush package import/export now use service-owned `std::jthread` workers and
   UI-thread completion handoff
-- canvas, grid, preview, and event-side detached work is still open
+- prepared-file save work and grid lightmap launch now also use service-owned
+  workers with explicit UI-thread handoff
+- canvas, preview, document export, and recording-side detached work are still
+  open
 
 Write scope:
 - `src/canvas.cpp`
@@ -547,8 +555,10 @@ which means the platform layer is not a platform layer yet.
 Current slice:
 - Linux FPS title updates now route through an injected callback installed from
   `App::set_platform_services()`
-- Apple singleton reach and the remaining platform callback surface are still
-  open
+- `platform_apple` clipboard, display/share, cursor, and save-ui-state calls
+  now route through injected Apple bridge callbacks instead of `App::I`
+- retained Apple callback injection and broader `platform_legacy` singleton
+  reach are still open
 
 Write scope:
 - `src/platform_apple/*`