fn parse_volume_spec(spec: &str) -> Option<(&str, &str, bool)>Expand description
Parse a Docker volume spec into (source, target, read_only).
Format: source:target or source:target:options.
Handles Windows drive-letter bind paths (e.g. C:\Users\me\repo:/workspace:ro)
by treating the drive-letter colon (X:) as part of the source path, not as
the source/target separator. A plain splitn(3, ':') would split C:\path
into C and \path, losing the drive letter.
Returns None for malformed specs (no target separator found).