feat(daemon): route commands and the TUI through a running daemon

Session::open attaches to a daemon when one is reachable and logs in
otherwise, so every existing command works unchanged against either. A local
socket is found automatically, which is what makes an agent's invocation need
no flags at all; --no-daemon opts out.

Commands now read identity, shares, server, and download directory from the
session rather than from this run's config: routed to a daemon those differ,
and the session is the one actually on the network. Without that, whoami
named the wrong server and shares reindex would have imposed the client
machine's folders on the daemon.

soulseek-rs/src/directories.rs

@@ -37,6 +37,7 @@ pub fn resolve_shared_directory(
 
 /// Validate several configured share paths; invalid ones are skipped with a
 /// warning instead of aborting (the client just shares less).
+#[must_use]
 pub fn resolve_shared_directories(dirs: &[String]) -> Vec<String> {
     let mut resolved = Vec::new();
     for dir in dirs {