DRY up eval I/O duplicated across scripts/eval-list.ts,
eval-compare.ts, and eval-summary.ts. Adds EVAL_DIR constant,
formatTimestamp(), listEvalFiles(), loadEvalResults() with
--limit support. 13 new tests.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
DRY up atomicWriteSync, readJSON, getGitInfo, getVersion, getRemoteSlug,
and sanitizeForFilename from eval-store.ts, session-runner.ts, and
eval-watch.ts into a shared module.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>