Extract app runtime tail, canvas camera shell, and preview sample services

docs/modernization/roadmap.md

@@ -79,15 +79,15 @@ What is still carrying too much live ownership:
 
 Current hotspot files:
 
-- `src/canvas.cpp`: 396 lines
+- `src/canvas.cpp`: 368 lines
 - `src/app_layout.cpp`: 125 lines
 - `src/canvas_modes.cpp`: 402 lines
 - `src/node.cpp`: 260 lines
 - `src/main.cpp`: 130 lines
 - `src/node_panel_brush.cpp`: 255 lines
-- `src/node_stroke_preview.cpp`: 545 lines
+- `src/node_stroke_preview.cpp`: 490 lines
 - `src/node_canvas.cpp`: 219 lines
-- `src/app.cpp`: 171 lines
+- `src/app.cpp`: 113 lines
 - `src/app_dialogs.cpp`: 168 lines
 
 Current architecture mismatches that must be treated as real blockers:
@@ -235,7 +235,11 @@ Current architecture mismatches that must be treated as real blockers:
   now live in `src/legacy_app_frame_services.cpp` instead of staying inline in
   `src/app.cpp`, while the larger document/export/save/open/thumbnail
   document-IO cluster now lives in `src/legacy_canvas_document_io_services.cpp`
-  and `src/app.cpp` is materially thinner,
+  and `src/app.cpp` is materially thinner, while `App::clear()`,
+  `App::check_license()`, `App::async_start()`, `App::async_redraw()`,
+  `App::async_end()`, and `App::async_swap()` now also live in
+  `src/legacy_app_runtime_shell_services.cpp` instead of staying inline in
+  `src/app.cpp`,
   while the canvas state-management cluster for picking, clear/clear-all, layer
   add/remove/order/lookups, animation frame control, resize, and snapshot
   save/restore now lives in `src/legacy_canvas_state_services.cpp` instead of
@@ -291,7 +295,9 @@ Current architecture mismatches that must be treated as real blockers:
   `Canvas::stroke_update(...)`, and `Canvas::stroke_start(...)` now also route
   through `src/legacy_canvas_stroke_runtime_services.*` instead of staying
   inline in `src/canvas.cpp`, which trims another large retained stroke/runtime
-  pocket, while the
+  pocket, while the final camera/timelapse member definitions now also live in
+  `src/legacy_canvas_camera_services.cpp` instead of staying inline in
+  `src/canvas.cpp`, which trims another retained canvas shell 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
@@ -381,7 +387,11 @@ Current architecture mismatches that must be treated as real blockers:
   `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`.
+  inline in `src/node.cpp`, while the preview sample execution pocket for
+  sample-point conversion, brush vertex upload, request assembly, and the
+  `execute_legacy_canvas_stroke_sample(...)` call now also lives in
+  `src/legacy_node_stroke_preview_sample_services.*` instead of staying inline
+  in `src/node_stroke_preview.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

docs/modernization/tasks.md

@@ -152,6 +152,9 @@ Current slice:
   `src/legacy_canvas_plane_data.cpp` instead of staying inline in
   `src/canvas.cpp`, which trims another retained data-ownership pocket from
   the live canvas shell.
+- The final camera/timelapse member definitions now also live in
+  `src/legacy_canvas_camera_services.cpp` instead of staying inline in
+  `src/canvas.cpp`, which trims another retained canvas shell pocket.
 - The `CanvasModePen` and `CanvasModeLine` interaction families now also live
   in `src/legacy_canvas_mode_pen_line.cpp` instead of staying inline in
   `src/canvas_modes.cpp`, which materially thins another retained pen/line
@@ -346,6 +349,12 @@ Current slice:
   `src/legacy_node_stroke_preview_runtime_services.*` instead of staying
   inline in `src/node_stroke_preview.cpp`, which trims another coherent
   preview runtime pocket while preserving the current live draw path.
+- The preview sample execution pocket for sample-point conversion, brush
+  vertex upload, request assembly, and the
+  `execute_legacy_canvas_stroke_sample(...)` call now also lives in
+  `src/legacy_node_stroke_preview_sample_services.*` instead of staying inline
+  in `src/node_stroke_preview.cpp`, which trims another coherent preview
+  execution pocket while preserving the live draw path.
 - `NodeCanvas::init()` plus the remaining `NodeCanvas::draw()` outer shell now
   also live in `src/legacy_node_canvas_draw_services.*` instead of staying
   inline in `src/node_canvas.cpp`, which materially reduces the live node to a
@@ -569,6 +578,11 @@ Current slice:
   instead of staying inline in `src/app.cpp`, which reduces the remaining app
   file to a thinner retained composition surface around startup and runtime
   delegation.
+- `App::clear()`, `App::check_license()`, `App::async_start()`,
+  `App::async_redraw()`, `App::async_end()`, and `App::async_swap()` now also
+  live in `src/legacy_app_runtime_shell_services.cpp` instead of staying
+  inline in `src/app.cpp`, which reduces the remaining app file to a thinner
+  retained shell around document routing and runtime thread entrypoints.
 
 Write scope:
 - `src/app.cpp`