Extract draw toolbar and thin NodeCanvas and Win32 shell

docs/modernization/roadmap.md

@@ -80,13 +80,13 @@ What is still carrying too much live ownership:
 Current hotspot files:
 
 - `src/canvas.cpp`: 2645 lines
-- `src/app_layout.cpp`: 353 lines
+- `src/app_layout.cpp`: 285 lines
 - `src/canvas_modes.cpp`: 1798 lines
 - `src/node.cpp`: 1594 lines
-- `src/main.cpp`: 487 lines
+- `src/main.cpp`: 434 lines
 - `src/node_panel_brush.cpp`: 1197 lines
 - `src/node_stroke_preview.cpp`: 890 lines
-- `src/node_canvas.cpp`: 910 lines
+- `src/node_canvas.cpp`: 881 lines
 - `src/app.cpp`: 502 lines
 - `src/app_dialogs.cpp`: 142 lines
 
@@ -129,7 +129,10 @@ Current architecture mismatches that must be treated as real blockers:
   `make_legacy_canvas_draw_merge_layer_path_gl_execution(...)` even though the
   remaining draw lambdas and broader node draw loop still live in
   `src/node_canvas.cpp`, where the post-draw/display-resolve tail now also
-  routes through `execute_node_canvas_draw_merge_tail(...)`.
+  routes through `execute_node_canvas_draw_merge_tail(...)`, while the
+  unmerged-path onion-range planning, plane filtering, per-layer visit
+  handling, and per-visit layer-path execution now also route through
+  `execute_legacy_canvas_draw_unmerged_node_canvas_shell(...)`.
 - `app_layout.cpp` and `app_dialogs.cpp` are still mixed shell/controller files
   rather than thin composition/binding surfaces, even though tools-menu binding
   plus nested panels/options submenu wiring now live in
@@ -146,8 +149,9 @@ Current architecture mismatches that must be treated as real blockers:
   binding now also lives in `src/app_layout_edit_menu.cpp` and
   `App::init_menu_edit()` is now a thin call-through, while UI-direction and
   persisted floating/docked panel-state ownership now also live in
-  `src/app_layout_ui_state.cpp`, and `src/app_layout.cpp` is now mostly
-  layout/bootstrap composition, while the
+  `src/app_layout_ui_state.cpp`, while draw-toolbar binding now also lives in
+  `src/app_layout_draw_toolbar.cpp`, and `src/app_layout.cpp` is now mostly
+  brush-refresh and layout/bootstrap composition, while the
   informational overlay opener family now also lives in
   `src/app_dialogs_info_openers.cpp` and the corresponding `App::dialog_*`
   entrypoints are thinner, while the export/video/PPBR dialog family now also
@@ -195,7 +199,9 @@ Current architecture mismatches that must be treated as real blockers:
   `src/platform_windows/windows_bootstrap_helpers.*` for runtime-data
   discovery, startup-state initialization, window creation, pixel-format
   setup, GL loader init, runtime-info logging, and core-context upgrade
-  sequencing, while the Win32 window procedure and retained message-handling
+  sequencing, while BugTrap/SEH recovery setup now also lives in
+  `src/platform_windows/windows_bootstrap_helpers.cpp` instead of
+  `src/main.cpp`, while the Win32 window procedure and retained message-handling
   shell now also live in `src/platform_windows/windows_window_shell.*`
   instead of `src/main.cpp`, which materially thins `src/main.cpp` even
   though broader entrypoint/runtime composition still remains there,

docs/modernization/tasks.md

@@ -225,6 +225,11 @@ Current slice:
   `execute_legacy_canvas_draw_unmerged_shell(...)`, which removes another
   coherent orchestration block from `NodeCanvas::draw()` even though the
   broader node draw loop still lives in `src/node_canvas.cpp`.
+- `NodeCanvas` unmerged-path onion-range planning, plane filtering, per-layer
+  visit handling, and per-visit layer-path execution now also route through
+  `execute_legacy_canvas_draw_unmerged_node_canvas_shell(...)`, which trims
+  another outer draw-shell block even though the broader node draw loop still
+  lives in `src/node_canvas.cpp`.
 
 Write scope:
 - `src/node_stroke_preview.cpp`
@@ -303,7 +308,7 @@ targets look like helpers under one old monolith.
 Status: In Progress
 
 Why now:
-`src/app_layout.cpp` is still a 353-line mixed file that builds menus,
+`src/app_layout.cpp` is still a 285-line mixed file that builds menus,
 attaches callbacks, computes planner inputs, and mutates UI state directly.
 
 Current slice:
@@ -333,6 +338,9 @@ Current slice:
 - UI-direction plus persisted floating/docked panel-state ownership now also
   lives in `src/app_layout_ui_state.cpp`, and `src/app_layout.cpp` is down to
   the remaining draw-toolbar, brush-refresh, and layout/bootstrap composition.
+- Draw-toolbar binding now also lives in `src/app_layout_draw_toolbar.cpp`, and
+  `src/app_layout.cpp` is down to the remaining brush-refresh and
+  layout/bootstrap composition.
 
 Write scope:
 - `src/app_layout.cpp`
@@ -498,6 +506,9 @@ Current slice:
   discovery, startup-state initialization, window creation, pixel-format
   setup, GL loader init, runtime-info logging, and core-context upgrade
   sequencing
+- BugTrap/SEH recovery setup now also lives in
+  `src/platform_windows/windows_bootstrap_helpers.cpp` instead of
+  `src/main.cpp`
 - the Win32 window procedure and retained message-handling shell now also live
   in `src/platform_windows/windows_window_shell.*` instead of `src/main.cpp`,
   which materially thins the entry file even though broader runtime/entrypoint