CLAUDE: Add fopen_turn_finder.py — find sharpest turns across all INTERFRAME.corr-xml

Scans all scene dirs under a linked data root, parses each
*-INTERFRAME.corr-xml (latest version subdir), and computes per-sequence
angular metrics for A/T/R axes:
  - range (max−min, deg)
  - vel1: max consecutive |Δangle|/Δt (deg/s) — fast, noise-sensitive
  - velW: max W-frame windowed |Δangle|/Δt (deg/s) — robust (default W=5)

A/T/R Cessna-nadir convention documented: R=heading, T=banking, A=pitch.
Sequence-length/altitude note documented: metrics are Δt-normalised.
Outputs ranked console tables and optional TSV.
Co-authored-by: Claude <claude@elphel.com>