Separate legacy declaration inputs from canonical serialized outputs
in IPC and architecture docs, and state the same-version registrar
tree contract while no wire-format negotiation exists.
Add PR #505's feature news fragment for `TunnelledAddress` and tagged
TCP/Unix output.
Review: PR #505 (goodboy)
https://github.com/goodboy/tractor/pull/505#pullrequestreview-5094473850
(this patch was generated in some part by `opencode` using `gpt-5.6-sol` (`openai`))
Gud Boi