README hadn't been touched since the early layer/viewport-only stage of
the project: it still described the removed LayerPanel, omitted the
Material Editor / MaterialPreviewRenderer / NodeThumbnailCache /
CurveEditorPanel / TimelinePanel entirely, and its Tests section
claimed ctest works even though BUILD_TESTS is OFF in every preset
(the two test executables have stale USD include paths, per
CLAUDE.md). Refreshes the feature list, architecture tree, and build
docs to match current source, and adds a screenshot gallery for the
Material Editor, Curve Editor, quad viewport, and MaterialX import.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
indigo