crmvec 0.7.1

• CORE-MATH: powf.c from master e3f1fcc, so all 165 of CORE-MATH's files are byte-identical to its master again. It removes an undefined shift (reported 2026-09-27) that cr_powf(0x1.ffff36p-1f, 0x1.03ac88p+24f) reaches in 0.7.0. No changed result was found: 0 differences from 0.7.0's powf on 2.7 billion pairs in the four rounding modes, and none among 40.7 million exact results in round-upward.
• Nothing else changes.