Move canvas import export GL mappings to renderer gl

docs/modernization/build-inventory.md

@@ -224,6 +224,8 @@ Known local toolchain state:
   Canvas layer merge rendering and explicit layer-merge compositing also consume
   backend-owned depth/blend state, active texture units, fallback 2D texture
   unbind targets, and merge framebuffer copy targets.
+  Canvas equirectangular import drawing and depth export rendering also consume
+  backend-owned depth/blend state and active texture units.
 - `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

@@ -768,6 +768,9 @@ Results:
 - Canvas layer merge rendering and explicit layer-merge compositing now route
   depth/blend state, active texture units, fallback 2D texture unbinds, and
   merge framebuffer copy targets through the renderer GL backend mapping.
+- Canvas equirectangular import drawing and depth export rendering now route
+  depth/blend state and active texture units 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.