feat(config): remember which daemon to use, and document the download box

A remote daemon could only be named with --daemon and --daemon-token on every
invocation, which made the one workflow daemon mode is most useful for — a
headless download box driven from a laptop — a matter of retyping a 64-character
token. Both are now config keys, so it is two 'config set' commands once and
plain commands thereafter.

Fixes a bug that setup exposed: the up-front daemon status probe read the token
from the command line only, so with the token in the config file it failed
silently and every command that names a path or a server fell back to this
machine's defaults — whoami claiming downloads land in the laptop's home
directory when they land on the box. The regression test was checked by
reintroducing the bug.

Documents the download-box workflow in plain terms across the README, the
website and the agent skill, and says plainly that the schema is open: OpenRPC,
served by the daemon itself, so an Android, iOS or web remote is something
anyone can build without asking.

soulseek-rs/src/SKILL.md

@@ -165,6 +165,13 @@ accepts connections from other machines, which need the token.
 **`daemon token`** — the secret a client on another machine needs. Local
 clients never need it.
 
+The daemon can also be on a *different* machine — a home server or NAS doing
+the downloading. Point at it once with `config set daemon host:5030` and
+`config set daemon_token <token>`, and every command afterwards drives that
+machine; files land there, not here. The interface is an open JSON-RPC schema
+(`rpc.discover` serves it), so a purpose-built client is a reasonable thing to
+write.
+
 **`shares list`** — one object per configured folder: `directory`, `usable`.
 **`shares add <directory>`** and **`shares remove <directory>`** — change the
 config file; they print nothing. With a daemon running they also update it in