* s3: commit a versioned PutObject and its latest pointer in one transaction
A versioned PutObject wrote the version file and flipped the .versions
latest pointer in two separate routed transactions. Fold the
RECOMPUTE_LATEST into the version file's PUT so both commit atomically
under the object's per-path lock: the recompute, applied after the PUT in
the same transaction, scans the directory and sees the new version. A
crash can no longer leave the version present with a stale pointer.
putToFiler now takes a putFinalize describing the finalize step — routed
mutations folded into the PUT, or an afterCreate run under the object
write lock off the ring. Suspended-versioning keeps its afterCreate-only
form; multipart, copy, and delete-marker finalizes are unchanged.
* s3: trim verbose finalize comments