Extract menu, stylus, and canvas draw helpers

docs/modernization/tasks.md

@@ -193,6 +193,10 @@ Current slice:
   remaining per-layer render-path orchestration now also routes through
   `execute_legacy_canvas_draw_merge_layer_path(...)`, but the node still owns
   broader draw-loop and renderer-state shell sequencing.
+- `NodeCanvas` outer non-`draw_merged` layer/plane traversal, onion-range
+  failure handling, and visit payload setup now also route through
+  `execute_legacy_canvas_draw_layer_traversal(...)`, but the node still owns
+  the heavier per-layer GL setup and draw lambdas.
 
 Write scope:
 - `src/node_stroke_preview.cpp`
@@ -271,7 +275,7 @@ targets look like helpers under one old monolith.
 Status: In Progress
 
 Why now:
-`src/app_layout.cpp` is still a 1360-line mixed file that builds menus,
+`src/app_layout.cpp` is still a 1249-line mixed file that builds menus,
 attaches callbacks, computes planner inputs, and mutates UI state directly.
 
 Current slice:
@@ -283,6 +287,10 @@ Current slice:
   `src/app_layout_file_menu.cpp`, and `App::init_menu_file()` is now a thin
   call-through, but about/layer/sidebar and broader layout composition are
   still inline in `src/app_layout.cpp`.
+- About-menu and layer-menu wiring now also live in
+  `src/app_layout_about_layer_menu.cpp`, and `App::init_menu_about()` plus
+  `App::init_menu_layer()` are now thin call-throughs, but edit/sidebar and
+  broader layout composition are still inline in `src/app_layout.cpp`.
 
 Write scope:
 - `src/app_layout.cpp`
@@ -405,6 +413,10 @@ Current slice:
   pair during initialization and context recreation
 - `main.cpp` main-thread queued task state now sits behind a narrow retained
   helper instead of `RetainedState.main_tasklist` / `main_task_mutex` directly
+- Win32 pointer API loading, stylus/ink timer ownership and decay, `WT_PACKET`
+  reset, and `WM_POINTERUPDATE` pen/touch handling now live in
+  `src/platform_windows/windows_stylus_input.cpp` instead of `src/main.cpp`,
+  but broader retained Win32 shell state is still open
 - prepared-file background work now runs through an `AppRuntime`-owned worker
   queue instead of a retained static worker in `src/app_events.cpp`
 - canvas async import/export/save/open background work now also runs through an