v6.1.0 — latest legacy-pipeline run addendum (docs)

Docs-only minor release. The G5 cohort of record stays v6.0.0 (kv4i1404_g00581_29ea3c73), and the paper of record is unchanged.

Adds a labeled addendum to the README and white paper, plus docs/LATEST_RUN.md, covering the latest legacy-pipeline continuous island run (xbabe2, i001-i103, stopped 2026-10-29). The best design, ec2i089_r01_p10_c68, scored fitness 80.851214 at 83.409 g and met 13 of 26 legacy hard gates. It is not qualified for use. Evidence is in evidence/legacy_continuous_run_v6.1.0/.