v0.145.0

BREAKING CHANGE

• nc_webdav_write_file no longer silently overwrites an
  existing file. Omitting if_match now creates a file and fails if it already
  exists; to overwrite, pass the etag from nc_webdav_read_file, or if_match="*"
  to force it.

Fix

• webdav: make writes fail-closed to guarantee zero data loss
• webdav: detect concurrent edits and locks on write, guard oversized writes

Refactor

• webdav: extract write precondition/conflict helpers (Sonar S3776)