Extract canvas live stroke, node canvas state, and preset panel UI

docs/modernization/roadmap.md

@@ -79,14 +79,14 @@ What is still carrying too much live ownership:
 
 Current hotspot files:
 
-- `src/canvas.cpp`: 2122 lines
+- `src/canvas.cpp`: 1490 lines
 - `src/app_layout.cpp`: 125 lines
 - `src/canvas_modes.cpp`: 1014 lines
 - `src/node.cpp`: 995 lines
 - `src/main.cpp`: 271 lines
-- `src/node_panel_brush.cpp`: 652 lines
+- `src/node_panel_brush.cpp`: 435 lines
 - `src/node_stroke_preview.cpp`: 751 lines
-- `src/node_canvas.cpp`: 877 lines
+- `src/node_canvas.cpp`: 702 lines
 - `src/app.cpp`: 575 lines
 - `src/app_dialogs.cpp`: 168 lines
 
@@ -260,7 +260,11 @@ Current architecture mismatches that must be treated as real blockers:
   larger stroke commit/sample execution family now also route through
   `src/legacy_canvas_stroke_commit_services.*` instead of staying inline in
   `src/canvas.cpp`, which trims another large retained stroke-render and
-  viewport-state execution family from the live canvas shell, while the
+  viewport-state execution family from the live canvas shell, while the live
+  `Canvas::stroke_draw()` orchestration now also routes through
+  `src/legacy_canvas_stroke_live_services.cpp` instead of staying inline in
+  `src/canvas.cpp`, which materially thins another large retained live
+  stroke-render pocket, while the
   `CanvasModeTransform` interaction family now also routes through
   `src/legacy_canvas_mode_transform.cpp` instead of staying inline in
   `src/canvas_modes.cpp`, which materially thins another retained canvas-view
@@ -273,10 +277,19 @@ Current architecture mismatches that must be treated as real blockers:
   import/export/import-ABR routing now also lives in
   `src/legacy_brush_preset_services.*` instead of staying inline in
   `src/node_panel_brush.cpp`, which trims another large preset-workflow pocket
-  from the live UI node, while `NodeCanvas::handle_event()` now also routes
+  from the live UI node, while `NodePanelBrushPreset` init/menu wiring, click
+  handling, item construction, and added-state update now also route through
+  `src/legacy_brush_preset_panel_ui.*` instead of staying inline in
+  `src/node_panel_brush.cpp`, which materially thins another retained preset
+  panel UI pocket, while `NodeCanvas::handle_event()` now also routes
   through `execute_node_canvas_handle_event(...)`, which trims another coherent
   input-routing block from `src/node_canvas.cpp` even though the file is still
-  a live canvas/controller shell, while shared canvas-mode GL wrappers plus the
+  a live canvas/controller shell, while `NodeCanvas` restore/clear context,
+  resize handling, camera reset, buffer creation, cursor visibility/update,
+  tick, and destroy ownership now also route through
+  `src/legacy_node_canvas_state_services.*` instead of staying inline in
+  `src/node_canvas.cpp`, which materially thins another retained state/control
+  pocket, while shared canvas-mode GL wrappers plus the
   `CanvasModeBasicCamera` and `CanvasModeCamera` input handlers now also route
   through `src/legacy_canvas_mode_helpers.*` instead of staying inline in
   `src/canvas_modes.cpp`, while