Route RTT blit readback through renderer GL

docs/modernization/build-inventory.md

@@ -467,8 +467,10 @@ Known local toolchain state:
   tested generic capability/buffer-clear dispatch consumed by VR draw state
   setup, tested saved-state snapshot/restore dispatch consumed by the retained
   `gl_state` utility, tested texture lifecycle/readback dispatch consumed by
-  the retained `Texture2D` utility, plus renderer API to OpenGL token mapping
-  and command-planning contracts used by the OpenGL parity work.
+  the retained `Texture2D` utility, tested framebuffer blit/readback dispatch
+  consumed by retained `RTT` resize/copy/readback paths, plus renderer API to
+  OpenGL token mapping and command-planning contracts used by the OpenGL parity
+  work.
 - `pano_cli plan-cloud-upload` exposes `pp_app_core` cloud upload availability,
   new-document warning, publish prompt, and save-before-upload planning as JSON;
   the live cloud upload command consumes the same start contract before

docs/modernization/roadmap.md

@@ -544,6 +544,9 @@ Legacy `Texture2D` allocation, binding, deletion, mipmap generation, region
 update, and framebuffer readback now execute through tested `pp_renderer_gl`
 texture dispatch contracts. This keeps the app API stable while moving another
 resource lifecycle path behind the renderer backend boundary.
+Legacy `RTT` resize/copy blits and byte/float framebuffer readbacks now execute
+through tested `pp_renderer_gl` framebuffer dispatch contracts with draw/read
+framebuffer binding restore handled by the backend helper.
 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.