Link the agent half of user/ on the Mac mini

Manifest lines can now name an OS. The SSH config, pwswitch and espanso are
Linux only, so link-user on the Mac links CLAUDE.md, rules, skills and the
opencode commands and nothing else. link-mcp no longer aborts under the Mac's
bash 3.2 when a server has no token.

user/README.md

@@ -86,6 +86,12 @@ Put the file under `user/`, add a line to `manifest`, run:
 Anything already at the destination is moved to `config/old/` rather than
 deleted, under a name that says where it came from.
 
+A line can end with `linux` or `darwin` to apply only on that OS. The Mac mini
+is not a Panama desktop, but it runs agents, so it takes the agent half of this
+directory and skips the SSH config, `pwswitch` and espanso. Panama's shipped
+skills describe the Linux desktop, so the Mac runs `link-user` and `link-mcp`
+only, never `link-skills`.
+
 ## What does not go in here
 
 Anything secret. This repository is readable by anyone who finds it, and the