Move canvas action pixel mapping to renderer gl

docs/modernization/build-inventory.md

@@ -1,7 +1,7 @@
 # Build And Platform Inventory
 
 Status: live
-Last updated: 2026-06-01
+Last updated: 2026-06-02
 
 This inventory records the known build surfaces during the CMake migration.
 Keep it updated as platform paths move to shared CMake targets.
@@ -164,7 +164,9 @@ Known local toolchain state:
   used before runtime capability detection are cataloged here. Legacy font
   atlas texture formats, text mesh buffer targets, attribute component and
   normalization tokens, draw primitive/index type, upload usage, and active
-  texture unit selection also consume the backend mapping.
+  texture unit selection also consume the backend mapping. Canvas undo/redo
+  dirty-region texture updates and readbacks also consume the backend-owned 2D
+  texture target, RGBA pixel format, and unsigned-byte component mapping.
 - `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.