docs: put daemon mode on the website and tighten the README

The website made three claims daemon mode falsifies — "No TTY, no daemon",
"no daemon, no MCP server, no API key", and "no GUI and no daemon mode yet"
under what-this-is-not. All three corrected.

Adds a docs section and a home feature card, both leading with the reason
rather than the mechanics: the server allows one session per account, so
parallel one-shot commands either displace each other or mean a throwaway
username per run, which is account churn on infrastructure other people
maintain. A daemon is one login for as long as you work.

The README section said that three times over and buried the reasoning below
the mechanics; rewritten to state it once, up front. It now also covers which
commands stay local and that shares add reaches a running daemon, which was
meant to land earlier and silently did not — the edit anchored on text that
only existed in SKILL.md.

website/src/pages/community.tsx

@@ -194,8 +194,7 @@ export const Community = () => {
           eyebrow="what this is not"
           title="Three good clients to point you elsewhere."
         >
-          soulseek-rs has no GUI and no daemon mode yet. If one of these fits you better,
-          use it.
+          soulseek-rs has no graphical interface. If one of these fits you better, use it.
         </SectionHead>
         <div className="grid grid-cols-1 gap-3.5">
           {ALTERNATIVES.map((alt) => (