Rework the shimmer-text CSS to use a Cursor-style sweep: full-opacity base
with a narrow transparent highlight band that slides across, linear timing,
tighter background-size. Add a "Status tokens" section to the Issue Chat UX
Lab showing both the active shimmer "Working" state and the static "Worked"
state side-by-side for quick visual review.
Co-Authored-By: Paperclip <noreply@paperclip.ing>
