Skeleton for the TypeScript implementation of DateKeys v0.8.x: the plans
in docs/, testdata/ vendored from g.activething.com/go/DateKeys at 5719f6a
with a zero-dependency sync and check script, and the TypeScript and vitest
tooling already used by the prototype, which now lives in ../AppOld.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
