_farther_unrelated searched for grade-1 reflectors whose cga_inner
score was below the prompt score. Field states are even-grade
(grade 0+2+4), so cga_inner with a grade-1 reflector is always zero
— making the search impossible when prompt_score is negative.
Replaced with _random_rotor (product of two reflectors) which lives
in the same even-grade subspace and produces nonzero inner products.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
