Create animation documents from pano cli

docs/modernization/build-inventory.md

@@ -96,6 +96,8 @@ Known local toolchain state:
   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.
+- `pano_cli create-document` supports `--frames` and `--frame-duration-ms` and
+  is covered by `pano_cli_create_animation_document_smoke`.
 - `panopainter_validate_shaders` validates the current combined GLSL shader
   files for one vertex stage marker, one fragment stage marker, valid marker
   order, and existing relative includes.