Extract canvas mask modes, preview draw pass, and node style shell

docs/modernization/roadmap.md

@@ -81,11 +81,11 @@ Current hotspot files:
 
 - `src/canvas.cpp`: 429 lines
 - `src/app_layout.cpp`: 125 lines
-- `src/canvas_modes.cpp`: 720 lines
-- `src/node.cpp`: 465 lines
+- `src/canvas_modes.cpp`: 402 lines
+- `src/node.cpp`: 389 lines
 - `src/main.cpp`: 271 lines
 - `src/node_panel_brush.cpp`: 435 lines
-- `src/node_stroke_preview.cpp`: 607 lines
+- `src/node_stroke_preview.cpp`: 562 lines
 - `src/node_canvas.cpp`: 219 lines
 - `src/app.cpp`: 292 lines
 - `src/app_dialogs.cpp`: 168 lines
@@ -347,7 +347,16 @@ Current architecture mismatches that must be treated as real blockers:
   `added_to_root()`, `handle_on_screen(...)`, template loading helpers, child
   add/remove/move helpers, and child query helpers now also route through
   `src/legacy_ui_node_tree_services.cpp` instead of staying inline in
-  `src/node.cpp`.
+  `src/node.cpp`, while the `CanvasModeMaskFree` and `CanvasModeMaskLine`
+  interaction families now also route through
+  `src/legacy_canvas_mode_mask.cpp` instead of staying inline in
+  `src/canvas_modes.cpp`, while the remaining live render/pass orchestration in
+  `NodeStrokePreview::draw_stroke_immediate()` now also routes through
+  `src/legacy_node_stroke_preview_draw_services.*` instead of staying inline in
+  `src/node_stroke_preview.cpp`, and while the generic Yoga
+  style/visibility pocket from `Node::SetWidth(...)` through `Node::GetRTL()`
+  now also routes through `src/legacy_ui_node_style.*` instead of staying
+  inline in `src/node.cpp`.
 - Modern C++23 usage exists in extracted components, especially `std::span`,
   explicit result/status objects, and a few concepts, but the live app still
   does not consistently express ownership, thread affinity, or renderer