[rmorgans]

Fixed

• S3 requests no longer end after 30 seconds. object_store's default
  request timeout runs from connecting to the end of the response body,
  so 0.7.0's single PUTs (up to 1 GiB) and any large GET failed on an
  ordinary uplink: at 85 Mbit/s about 320 MB fits in 30 s, less with jobs
  sharing it. Every S3 client bigstore builds now allows six hours per
  request and keeps the 5-second connect limit, with no per-read limit
  (a PUT's response read waits for the whole upload). A caller that builds
  its own client for large transfers needs the same.

Changed

• Single PUTs go up to 4 GiB (backend::SINGLE_PUT_MAX, was 1 GiB),
  inside the 5 GB that S3 and Wasabi document. Tracking runs write tables
  of up to 2 GB; at 1 GiB those went multipart, whose ETag is never the
  md5, so every S3 scrub read them back whole. The process-wide budget
  for single-PUT bodies held in memory is the same 4 GiB, counted in MiB
  units so it fits the semaphore.

Verified against real Wasabi from asset-store (drill, 2026-10-02): a 2,016,058,747-byte run table went up as one PUT with ETag == md5 (0.7.0 sent it as 193 parts and re-read it on every scrub); a no-op health against the peer fell from 355 s to 9 s; 2.2 GB synced in 406 s (0.7.0: 1007 s).