Share retained RTT clear dispatch

docs/modernization/roadmap.md

@@ -944,7 +944,8 @@ moving render-target pass entry/exit state management behind the backend.
 Legacy `RTT::clear`, `RTT::clear_mask`, `RTT::bindTexture`, and
 `RTT::unbindTexture` now dispatch through `pp_renderer_gl` clear,
 color-write-mask restore, and texture-bind contracts, keeping render-target
-utility operations behind the backend boundary.
+utility operations behind the backend boundary. The retained RTT clear and
+masked-clear callback endpoints now share `legacy_ui_gl_dispatch`.
 Windows RenderDoc frame capture hooks now also dispatch through
 `PlatformServices`, keeping capture integration in the platform service while
 leaving non-Windows adapters as no-ops.
@@ -2605,6 +2606,11 @@ Results:
   local raw callback clusters from `src/app.cpp`, `src/app_commands.cpp`, and
   `src/app_vr.cpp` while app/VR renderer execution remains retained under
   DEBT-0036.
+- Retained RTT clear and masked-clear endpoints now share
+  `legacy_ui_gl_dispatch` for boolean color-mask query, color-mask apply,
+  clear-color, and buffer-clear callbacks, removing the local raw clear
+  callback cluster from `src/rtt.cpp` while RTT render-target execution remains
+  retained under DEBT-0036.
 - Canvas draw-merge shader-blend selection now consumes the extracted
   `pp_paint_renderer` stroke composite planner for current layer and primary
   brush blend modes, while preserving legacy OpenGL compositing execution under