ainative-router: bagged policy (multiple-choice -> reasoning effort low)

Final policy is the per-category majority vote over 25 group-bootstrap refits on
the external calibration set, which stabilises near-tied options. Multiple-choice
moves to deepseek-v4.1-flash with reasoning effort low (same accuracy within noise,
~31% lower cost on calibration). Predictions regenerated; all rows valid.

Author: agent-studio-kr