Review feedback: split the anchor/path and path/suffix on the structural
delimiter ":/" instead of a bare ":". Since the path and suffix always
start with "/", ":/" is the real delimiter, and a ":" *inside* a file or
directory name (which OpenCloud allows but MS Graph/OneDrive forbid) is
kept as part of the path instead of being mistaken for a separator.
A ":" sitting at a segment boundary (e.g. a name ending in ":") stays
ambiguous and must be percent-encoded as "%3A": the split works on the
literal ":/", so "%3A" is never a delimiter and decodes back to ":". This
is now documented in the code and the acceptance feature.
Tests: colon inside a name (with and without a suffix), the Stat path
carrying the colon, and the "%3A" boundary escape.
b6a4a66aef