Function default_admin_addr 

pub fn default_admin_addr() -> PathBuf

Default admin endpoint path per platform. Mirrors the daemon’s endpoint::default_admin_addr so clients can reach the spec’d default without hard-coding it.

Linux resolution chain (per docs/protocol-v1.md §“Admin endpoint”):

1. $XDG_RUNTIME_DIR/inferd/admin.sock
2. $HOME/.inferd/run/admin.sock
3. /tmp/inferd/admin.sock