Long-running intraday auto-chunked queries emit no progress on stderr

[DTTerastar]

Severity

minor

Summary

prime warns that intraday "auto-chunks 24h slices, each rate-limited" and that wider windows take minutes. In practice the CLI runs silently for the entire window — no per-chunk progress on stderr, no "fetching 2026-04-20..." lines, nothing. Users running withings-export intraday --since 7d see a frozen terminal and have no way to tell whether it's working or hung.

Reproduce

$ withings-export intraday --since 2d 2>err >out
$ wc -c err
       0 err   <-- stderr is empty even on multi-chunk runs

Expected

Per the quantcli contract ("stderr = progress/errors"), emit one short progress line to stderr per chunk fetched, e.g.:

fetched 2026-04-23 (1241 samples)
fetched 2026-04-24 (1376 samples)

or a \\r-overwriting counter for terminals. Stdout must remain pure data so withings-export intraday --since 7d --format json > out.json keeps working.

Severity rationale

Minor because it's a UX gap, not a data bug. Promote to major if users start canceling in the middle of multi-day exports because they think it's hung.

[DTTerastar]

Confirmed still reproduces against HEAD b580683. /tmp/qa-bin/withings-export intraday --since 2d 2>err.log >out.log -> wc -l err.log is 0 even though stdout is 2381 lines / multiple chunks. No per-chunk progress emitted to stderr.