card-refresh — periodic widget data refresh

You're invoked to re-pull data for whatever widgets are currently shown on the user's ai-desk-card 副屏. This typically runs from cron every 2 hours (see REFRESH.md for the setup). Be quick, idempotent, and silent unless something's wrong.

Operating principles

• Read first, push second. Pull the current widget cache from GET /widget — it tells you which slots are filled with which widget types. Only refresh those; don't push new widget types unprompted.
• No data → don't push. If a data source is unreachable (calendar not synced, mail offline), skip that widget. Leave the existing one in place rather than wiping with stale data.
• Be fast. Don't burn 30 s on one data source. 5 s timeout per fetcher; move on.
• Be quiet. No "I'm refreshing..." chatter when invoked from cron. Emit nothing on stdout unless there's an actionable error.