Move early canvas GL mappings to renderer gl

docs/modernization/build-inventory.md

@@ -214,6 +214,10 @@ Known local toolchain state:
   brush/stencil/mix sampler filters and wraps, and image channel-count texture
   formats for cube-strip imports. Clamp-to-border sampler wrap is now part of
   the backend capability catalog and test coverage.
+  Early canvas draw helpers also consume backend-owned pick readback
+  format/type, stroke mixer depth/scissor/blend state, saved viewport and
+  clear-state queries, active texture units, fallback 2D texture unbind
+  targets, and stroke background copy targets.
 - `windows-msvc-vcpkg-headless` validates manifest install/configure/build/test
   for the current headless component matrix; see DEBT-0007 for remaining app
   and platform triplet migration.

docs/modernization/roadmap.md

@@ -758,6 +758,10 @@ Results:
   filters and wraps, and cube-strip import channel formats through the renderer
   GL backend mapping. The clamp-to-border sampler wrap is now cataloged and
   tested in `pp_renderer_gl`.
+- Early canvas draw helpers now route pick readbacks, stroke mixer depth/scissor
+  and blend state, saved viewport/clear-state queries, active texture units,
+  fallback 2D texture unbinds, and stroke background copy targets through the
+  renderer GL backend mapping.
 - Known remaining warnings: legacy project/vendor diagnostics, Visual Studio
   vcpkg-manifest warning, `LNK4099` missing libyuv PDBs, and `LNK4098` runtime
   library conflict from retained vendor binaries.