Validate renderer shader descriptors

docs/modernization/build-inventory.md

@@ -88,7 +88,8 @@ Known local toolchain state:
   `pp_ui_core`, `pano_cli`, and their current headless test binaries,
   including foundation event/logging/task queue coverage, PNG metadata, PPI
   header, settings document, document frame move/duration coverage, paint
-  brush/stroke coverage, UI color parsing, and layout XML parse coverage.
+  brush/stroke coverage, renderer shader descriptor coverage, UI color
+  parsing, and layout XML parse coverage.
 - `pano_cli inspect-image` reports PNG IHDR metadata as JSON and is covered by
   `pano_cli_inspect_png_metadata_smoke` with a tiny IHDR fixture.
 - `panopainter_validate_shaders` validates the current combined GLSL shader