Extract main toolbar and thin startup/node helpers

docs/modernization/tasks.md

@@ -293,7 +293,7 @@ targets look like helpers under one old monolith.
 Status: In Progress
 
 Why now:
-`src/app_layout.cpp` is still a 1249-line mixed file that builds menus,
+`src/app_layout.cpp` is still a 743-line mixed file that builds menus,
 attaches callbacks, computes planner inputs, and mutates UI state directly.
 
 Current slice:
@@ -313,6 +313,9 @@ Current slice:
   `src/app_layout_sidebar.cpp`, and `App::init_sidebar()` is now a thin
   call-through, but edit-menu wiring and broader layout composition are still
   inline in `src/app_layout.cpp`.
+- Main-toolbar binding now also lives in `src/app_layout_main_toolbar.cpp`,
+  and `App::init_toolbar_main()` is now a thin call-through, but edit-menu
+  wiring and broader layout composition are still inline in `src/app_layout.cpp`.
 
 Write scope:
 - `src/app_layout.cpp`
@@ -473,6 +476,12 @@ Current slice:
   wakeup posting, stylus frame update, window preference save, and VR
   lifecycle wrappers now also live in
   `src/platform_windows/windows_lifecycle_shell.cpp` instead of `src/main.cpp`
+- `main.cpp` startup/window/bootstrap flow now also routes through named local
+  helpers for runtime-data discovery, startup-state initialization, window
+  creation, pixel-format setup, GL loader init, runtime-info logging, and
+  core-context upgrade sequencing, but the retained Win32 shell still needs
+  those helpers moved into platform-owned modules before the file materially
+  shrinks
 - 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
@@ -632,6 +641,12 @@ Why now:
 mixes raw `Node*`, shared ownership, direct `add_child(...)`, and callback
 captures across mutation points.
 
+Current slice:
+- `src/node.cpp` child attach/detach/reorder paths now route through named
+  local helpers instead of repeating raw mutation logic inline. That improves
+  scene-graph mutation clarity, but it does not yet change the ownership model
+  or move those paths behind checked handles.
+
 Write scope:
 - `src/node.*`
 - `src/layout.*`