Reconciled with main's keyframe labels (same Keyframe::label field; keys.setLabel and
keys.selectLabelGroup from main are kept, M14.5's duplicates removed; Edit ▸ Label on
selected keys delegates to the label helper), proxies (RenderOpts::proxy next to
nested_switches/draft_shadows), offloaded renders (Work carries nested_switches), wasm
audio pump (preview mix rate), variable font axes and mask feather points.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>