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

docs/modernization/tasks.md

@@ -91,7 +91,7 @@ Status: In Progress
 
 Why now:
 `src/canvas.cpp` is still the biggest single architectural blocker at about
-2122 lines, with `src/canvas_modes.cpp` still large at about 1014 lines.
+1490 lines, with `src/canvas_modes.cpp` still large at about 1014 lines.
 
 Current slice:
 - Canvas state-management helpers for picking, clear/clear-all, layer
@@ -126,6 +126,10 @@ Current slice:
   `src/legacy_canvas_mode_transform.cpp` instead of staying inline in
   `src/canvas_modes.cpp`, which materially thins another retained
   transform-mode pocket from the broader canvas/render hotspot family.
+- The live `Canvas::stroke_draw()` orchestration now also lives in
+  `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 from the canvas shell.
 
 Write scope:
 - `src/canvas.cpp`
@@ -289,6 +293,11 @@ Current slice:
   `execute_node_canvas_handle_event(...)` helper, which trims another coherent
   input-routing block from `src/node_canvas.cpp` even though the node still
   owns broader canvas/controller behavior.
+- `NodeCanvas` restore/clear context, resize handling, camera reset, buffer
+  creation, cursor visibility/update, tick, and destroy ownership now also
+  live in `src/legacy_node_canvas_state_services.*` instead of staying inline
+  in `src/node_canvas.cpp`, which materially thins another retained
+  state/control pocket without reopening the draw path.
 
 Write scope:
 - `src/node_stroke_preview.cpp`
@@ -1011,6 +1020,12 @@ Current slice:
   in `src/node_panel_brush.cpp`, which trims another large preset-workflow
   pocket from the live UI node even though the broader cloud/package worker
   split still remains follow-up work.
+- `NodePanelBrushPreset` init/menu wiring, click handling, item construction,
+  and added-state update now also live in
+  `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 even though cloud/package worker ownership remains the
+  follow-up.
 
 Write scope:
 - `src/legacy_cloud_services.*`