Extract sidebar, lifecycle shell, and canvas unmerged draw

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`: 1249 lines
+- `src/app_layout.cpp`: 785 lines
 - `src/canvas_modes.cpp`: 1798 lines
 - `src/node.cpp`: 1551 lines
-- `src/main.cpp`: 909 lines
+- `src/main.cpp`: 882 lines
 - `src/node_panel_brush.cpp`: 1197 lines
 - `src/node_stroke_preview.cpp`: 933 lines
-- `src/node_canvas.cpp`: 905 lines
+- `src/node_canvas.cpp`: 910 lines
 - `src/app.cpp`: 502 lines
 - `src/app_dialogs.cpp`: 142 lines
 
@@ -138,7 +138,9 @@ Current architecture mismatches that must be treated as real blockers:
   live in `src/app_layout_file_menu.cpp` and `App::init_menu_file()` is now a
   thin call-through, while 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, while the informational
+  `App::init_menu_layer()` are now thin call-throughs, while sidebar panel
+  binding and popup wiring now also live in `src/app_layout_sidebar.cpp` and
+  `App::init_sidebar()` is now a thin call-through, 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 lives in
@@ -177,7 +179,10 @@ Current architecture mismatches that must be treated as real blockers:
   `src/main.cpp`, while RenderDoc startup/frame capture, SHCore DPI bootstrap,
   Win32 error-string conversion, and the GL debug pre/post callbacks now also
   live in `src/platform_windows/windows_bootstrap_helpers.cpp` instead of
-  `src/main.cpp`,
+  `src/main.cpp`, while Win32 lifecycle running-state, close/shutdown
+  sequencing, FPS title update/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`,
   while `App::rec_loop()` now delegates worker-iteration orchestration into
   the retained recording bridge, `App::update_rec_frames()` now delegates
   recording label refresh through that same retained recording path, and the