Second capture round (owner-driven): every frame carries the camera
pose from Render::viewer_pos, closing the FW0 pose gap. The
holtburg-transitions fixture records a full out-and-back doorway
crossing with all four root flips. README documents the P-line format
and the marker-timing caveat that gates still fixtures first.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
