v0.4.0

Added

• Per-request observability on both servers, alongside the existing stats():
  • report() — a high-level, JSON-serializable summary: totals plus by_label /
    by_status breakdowns (and, on ObjectStore, the metadata_requests /
    data_requests / other_requests split). Built from exact counters, so it stays
    complete even after the drill-down buffer rolls.
  • requests — the recent RequestRecord objects for drilling into individual
    requests: status, wire nbytes, byte range, injected latency_ms, total
    dur_ms, in_flight, label, and — on S3 — op and whether the write was
    conditional.
  • classify= to group keys for the by_label breakdown, and max_records= to cap the
    drill-down ring buffer (None = unbounded, 0 = counts only).
• Per-request logging via the stdlib loggers snailmail.http / snailmail.s3 (off until
  you add a handler / raise the level). The CLI gains --log to stream one line per
  request, and its stop summary now shows the status breakdown.
• ClientLink: a shared client uplink/downlink metered across multiple ObjectStores on
  top of each store's per-source bandwidth_mbs — for modelling an Icechunk store and the
  remote bucket it virtualizes contending for one connection. Asymmetric (down_mbs /
  up_mbs); ObjectStore-only for now.

Fixed

• HTTPRangeServer recorded 206 for well-formed but unsatisfiable range requests (a
  range past EOF, or any range against an empty file) where aiohttp actually sends 416;
  the recorded status now matches the wire.