Self's sequencing note (2026-09-22): the C# R-N pass (code/details on
cultnet.error.v0) is running separately in C:\ws3 and will report the
exact field names and code strings once it lands. Do not guess them.
Reverts the earlier Error{code,details} fields on CultNetMessage, the
SelectionRefusal::wire_code/wire_details/to_wire_message mapping, and
their five tests. R-O, R-T, R-U's hand-probes and R-R are unaffected -
none of them depend on the wire error shape. When the C# R-N commit
lands, pull it, read its exact field names and codes, and implement the
Rust mapping against those instead of a guess.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>