Extract stroke commit history mutation helpers

docs/modernization/tasks.md

@@ -1839,7 +1839,7 @@ ctest --preset desktop-fast --build-config Debug -R "pp_paint_renderer_stroke_ex
 
 ### STR-040 - Extract Stroke Commit Local History And Dirty Mutation
 
-Status: Ready
+Status: Done
 Score: +1 renderer boundary and OpenGL parity
 Debt: `DEBT-0036`
 Scope: `src/canvas.cpp`, `tests/paint_renderer/stroke_execution_tests.cpp`
@@ -1850,6 +1850,8 @@ Move the remaining local history and dirty-mutation work inside
 `make_canvas_stroke_commit_callbacks()` into a retained helper so the callback
 builder only forwards concrete canvas state.
 
+Closeout: `aa53a5f9`
+
 Done Checks:
 
 - `make_canvas_stroke_commit_callbacks()` no longer owns the history/dirty