v0.12.1

Bug fixes

• Daily history is now a continuous calendar. The "Daily Tokens (14 days)"
  and cost charts skipped days with no Claude usage, packing active days
  together so the date axis wasn't continuous. GetHistory now returns the full
  window of N days ending today, zero-filling idle days so they render as empty
  bars with their date labels. This also corrects a latent off-by-one where the
  window spanned N+1 days.

• Stopped a self-inflicted rate-limit storm after a rejected token. When the
  usage API rejected the access token with a 401, the poller marked auth expired
  but the next credential reload reset it to OK on the still-future local
  ExpiresAt, so polling resumed, drew another 401, and looped every 30s until
  the API returned 429. The auth provider now remembers the rejected token and
  stays expired until a genuinely different token is written to disk (i.e.
  Claude Code refreshed it), so the poller waits quietly instead of hammering
  the API.