Documents the 2026-04-26 split of faceset_001 (707 curated faces) into
6 substantive era buckets + 68 thin fragments, including the readiness
probe evidence, the anchor-based assignment rationale (replaces
transitive union-find that caused year-drift), and the re-run / apply-
to-other-identity workflow.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
