Move app open routing into document helper

docs/modernization/roadmap.md

@@ -84,11 +84,11 @@ Current hotspot files:
 - `src/canvas_modes.cpp`: 176 lines
 - `src/node.cpp`: 222 lines
 - `src/main.cpp`: 130 lines
-- `src/node_panel_brush.cpp`: 189 lines
+- `src/node_panel_brush.cpp`: 186 lines
 - `src/node_stroke_preview.cpp`: 192 lines
 - `src/node_canvas.cpp`: 69 lines
-- `src/app.cpp`: 113 lines
-- `src/app_dialogs.cpp`: 168 lines
+- `src/app.cpp`: 105 lines
+- `src/app_dialogs.cpp`: 106 lines
 
 Latest slice:
 
@@ -96,10 +96,21 @@ Latest slice:
   `handle_legacy_node_canvas_event(...)` in
   `src/legacy_canvas_tool_services.*`, leaving `src/node_canvas.cpp` as a much
   thinner controller shell.
+- `App::open_document()` now routes through
+  `src/legacy_document_open_services.cpp`, which moved the document route
+  classification and unsaved-project gating out of `src/app.cpp` and into the
+  retained document-open helper.
+- `App::dialog_layer_rename()` now routes through
+  `open_legacy_document_layer_rename_dialog(...)` in
+  `src/legacy_document_layer_services.*`, which moved the remaining
+  overlay-open/wire/close workflow out of `src/app_dialogs.cpp`.
 - The remaining low-level `NodeStrokePreview` viewport/query and texture-slot
   plumbing now lives in
   `src/legacy_node_stroke_preview_runtime_services.*` instead of staying
   inline in `src/node_stroke_preview.cpp`.
+- `NodePanelBrushPreset` global panel registration now lives in
+  `src/legacy_brush_preset_list_services.*` instead of staying on the live
+  node type as a static registry field.
 - The remaining generic `Node` geometry/state pocket for `SetSize(...)`,
   `SetMinSize(...)`, `SetMaxSize(...)`, and `SetPosition(const glm::vec2)` now
   lives in `src/legacy_ui_node_style.*` instead of staying inline in
@@ -185,8 +196,9 @@ Current architecture mismatches that must be treated as real blockers:
   lives in
   `src/app_dialogs_export.cpp` and those `App::dialog_*` entrypoints are
   thinner too, while new/open/save/browse/resize workflow entrypoints now also
-  live in `src/app_dialogs_workflow.cpp` and `src/app_dialogs.cpp` is now
-  mostly a thin dialog dispatch surface.
+  live in `src/app_dialogs_workflow.cpp`, while the layer-rename dialog open /
+  wire / close pocket now lives in `src/legacy_document_layer_services.*`, and
+  `src/app_dialogs.cpp` is now a thinner dialog dispatch surface.
 - `App`, `Canvas`, `Node`, retained workers, and platform entrypoints still use
   global singleton reach, raw observer pointers, retained static worker
   ownership in several app families, and ad hoc mutex/condition-variable
@@ -355,7 +367,11 @@ Current architecture mismatches that must be treated as real blockers:
   `src/legacy_brush_preset_panel_ui.*`
   instead of staying inline in `src/node_panel_brush.cpp`, which removes the
   last inline brush-panel popup close handler from the live node. The
-  broader preset workflow pocket still remains, while `NodeCanvas::handle_event()`
+  `NodePanelBrushPreset` registration/lifecycle pocket now also routes through
+  the preset-list helper registry instead of a node-local static vector,
+  which removes the remaining live preset-panel ownership glue from
+  `src/node_panel_brush.cpp`. The broader preset workflow pocket still remains,
+  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