Own main workers and narrow Apple render hooks

docs/modernization/tasks.md

@@ -131,6 +131,8 @@ 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` merged-path and non-blend checkerboard background setup now also
+  route through `execute_legacy_canvas_draw_merge_background_setup(...)`.
 - `NodeCanvas` display resolve plus cache-to-screen checkerboard/cache-texture
   composite now route through `legacy_canvas_draw_merge_services.h`.
 - `NodeCanvas` smoothing-mask overlay, smoothing-mask face pass, grid keepalive
@@ -370,6 +372,9 @@ modernization foundation.
 Current slice:
 - app-owned render/UI runtime queues and cloud worker ownership are already
   moving behind owned runtime/service objects
+- Windows splash-dialog and HMD renderer worker ownership in `main.cpp` now
+  also use `std::jthread` with explicit stop requests instead of raw
+  `std::thread`
 - brush package import/export now use service-owned `std::jthread` workers and
   UI-thread completion handoff
 - prepared-file save work and grid lightmap launch now also use service-owned
@@ -585,6 +590,9 @@ Current slice:
 - iOS virtual-keyboard visibility and prepared-file save handoff now also route
   through explicit Apple bridge callbacks instead of direct `App::I` calls in
   `LegacyPlatformServices`
+- Apple render-context acquire/release/present hooks and iOS
+  `bind_main_render_target()` now also route through explicit Apple bridge
+  callbacks instead of direct `App::I` calls in `LegacyPlatformServices`
 - retained Apple callback injection and broader `platform_legacy` singleton
   reach are still open