Extract renderer shader catalog

docs/modernization/roadmap.md

@@ -383,8 +383,9 @@ adding new backends.
 Status: started. `pp_renderer_api` exists as a headless renderer-neutral target
 with texture descriptor, byte-size, viewport, mesh, readback bounds, command
 context, render device, shader program descriptor, mesh, render target,
-readback, and trace interface validation. OpenGL classes are not yet behind
-these interfaces.
+readback, trace interface validation, and the canonical PanoPainter shader
+catalog now consumed by the legacy OpenGL app initialization path. OpenGL
+classes are not yet behind these interfaces.
 
 Implementation tasks:
 
@@ -592,7 +593,8 @@ Results:
 - `pp_document_ppi_import_tests` passed, including decoded PPI dirty-face
   payload attachment to `pp_document` layer/frame storage and out-of-range
   payload rejection.
-- `pp_renderer_api_tests` passed, including shader descriptor validation.
+- `pp_renderer_api_tests` passed, including shader descriptor validation,
+  PanoPainter shader catalog validation, and invalid catalog rejection.
 - `pp_paint_renderer_compositor_tests` passed.
 - `pp_ui_core_color_tests` passed.
 - `pp_ui_core_layout_value_tests` passed.