Move OpenGL runtime classification into renderer backend

docs/modernization/build-inventory.md

@@ -788,6 +788,10 @@ Known warnings after the current CMake app build:
   the retained OpenGL runtime classes still include legacy app/engine headers
   and are still consumed directly by canvas and UI classes. It should become a
   normal backend library once those call sites depend on `pp_renderer_api`.
+  `pp_renderer_gl` now owns OpenGL runtime build-target classification through
+  CMake target compile definitions and `opengl_runtime_for_current_build()`,
+  so app shader startup asks the backend for desktop GL/GLES/WebGL policy
+  instead of carrying local platform branches.
 - `pp_legacy_ui_core` is an object-library containment boundary because the
   retained base `Node` controls still depend on legacy renderer and app
   headers. It should shrink as layout parsing, colors, generic controls, and

docs/modernization/roadmap.md

@@ -672,6 +672,10 @@ Default canvas allocation size now dispatches through `PlatformServices`, so
 1536 and WebGL 512 defaults without carrying the old `CANVAS_RES` platform
 macro in `canvas.h`; DEBT-0057 tracks moving the retained WebGL policy branch
 out of the legacy fallback when the Web shell owns injected services.
+OpenGL runtime build-target classification now lives in `pp_renderer_gl`
+through CMake-owned compile definitions and
+`opengl_runtime_for_current_build()`, so `app_shaders.cpp` no longer decides
+desktop GL/GLES/WebGL capability policy with local platform branches.
 Prepared-file save/download handoff is now also part of the service contract,
 so iOS/Web export completion routes through `PlatformServices` after the app
 writes the temporary/exported payload.