CLAUDE: Add COLMAP sanity-check script

Verifies Phase 0 output before any OpenMVS tools run:
- camera intrinsics (focal length, FoV)
- camera-centre trajectory plots (XY/XZ/YZ)
- inter-frame step statistics with outlier detection
- consecutive rotation change (warns if > 10°)
- sample image display with NaN/saturation diagnostics

Fixed a stride-2 parse bug: empty 2D-point lines must be kept
in the line list before the range(0,N,2) loop, otherwise only
every other image record is parsed.

Co-authored-by: Claude <claude@elphel.com>