timeline.place kept a sub-frame start and rounded the duration to whole
frames, so the clip ran past time + duration and the sequence ended
between frames. The start and the end now each snap to the nearest frame,
as a timeline drag already does. sequence.inspect's durationFrames now
comes from the same frame_span export uses, so the two always agree.
Fixes#1101
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Play source video and audio, drag marked ranges as video, audio, or a linked pair, and route Source commands to clip marks and markers. Add shared draggable In/Out handles and range movement, preserving scrubber priority and explicit-only Program marks.
Include original code-drawn controls, documentation, attribution, and regression coverage for playback, placement, routing, undo, cancellation, and hostile parameters.
Assisted-by: Codex
