Merge patch series "Casefold Fixes"

Bring in a bunch of fixes for the casefold work.

* patches from https://patch.msgid.link/20260515153515.362266-1-cel@kernel.org:
  nfsd: Cap case-folding probe cost across READDIR entries
  nfsd: Map -ESTALE from case probe to NFS3ERR_STALE
  nfsd: Use kernel credentials for case-info probe
  fs: Clarify FS_CASEFOLD_FL semantics in UAPI header
  nfs: Skip pathconf probe when neither field is consumed
  nfs: Avoid transient zeroed case capability bits during probe
  tools headers UAPI: Sync case-sensitivity flags from linux/fs.h

Link: https://patch.msgid.link/20260515153515.362266-1-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>