v0.5.6 — the editor stops guessing at auth

[dea6cat]

• clyde --acp offers terminal login (clyde login) as its auth method and answers authenticate, which the ACP Registry requires of listed agents. With no provider connected, session/new replies with the protocol's auth-required error instead of leaving the editor waiting.
• Files you @-mention in an editor (Zed) now reach the model: it is told the path and line range and reads the file itself, so its permission and secret-file guards still apply.
• --acp no longer hangs the editor when a request makes Clyde exit: the editor gets an error reply.

---

This discussion was created from the release v0.5.6 — the editor stops guessing at auth.