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/cli.rs

@@ -25,6 +25,7 @@ Examples:
   soulseek-rs browse someuser --json            list a peer's shares
   soulseek-rs room listen lobby --follow        stream room chat
   soulseek-rs serve --follow --json             share files, stream upload events
+  soulseek-rs daemon                            run as a service; later commands use it
   soulseek-rs user someuser                     is this peer online and worth it
   soulseek-rs skills install                    teach your coding agent this CLI
   soulseek-rs completions install               tab completion for your shell
@@ -129,6 +130,23 @@ pub struct Cli {
     )]
     pub search_timeout: Option<u64>,
 
+    /// Control a daemon at this address (host:port) or Unix socket path
+    #[arg(long, global = true, env = "SOULSEEK_DAEMON", value_name = "ADDR")]
+    pub daemon: Option<String>,
+
+    /// Token for a remote daemon; a local socket needs none
+    #[arg(
+        long,
+        global = true,
+        env = "SOULSEEK_DAEMON_TOKEN",
+        hide_env_values = true
+    )]
+    pub daemon_token: Option<String>,
+
+    /// Ignore any running daemon and open this run's own session
+    #[arg(long, global = true, action = ArgAction::SetTrue)]
+    pub no_daemon: bool,
+
     /// Config file to read instead of the default location
     #[arg(long, global = true, env = "SOULSEEK_CONFIG", value_name = "FILE")]
     pub config: Option<PathBuf>,
@@ -183,6 +201,9 @@ pub enum Commands {
     /// Stay online sharing files, reporting each upload as it happens
     Serve(ServeArgs),
 
+    /// Run as a service other clients connect to, or control one that is
+    Daemon(DaemonArgs),
+
     /// What the server knows about another user
     User(UserArgs),
 
@@ -209,6 +230,33 @@ pub enum Commands {
     Completions(CompletionsCommand),
 }
 
+#[derive(Args, Debug, Default)]
+pub struct DaemonArgs {
+    #[command(subcommand)]
+    pub command: Option<DaemonCommand>,
+
+    /// Also accept control connections on this address, for clients on other
+    /// machines. They need the token; the local socket does not.
+    #[arg(long, value_name = "ADDR")]
+    pub bind: Option<String>,
+
+    /// How many uploads to serve at once
+    #[arg(long, value_parser = clap::value_parser!(u16).range(1..=1000))]
+    pub upload_slots: Option<u16>,
+}
+
+#[derive(Subcommand, Debug)]
+pub enum DaemonCommand {
+    /// Print the token remote clients authenticate with
+    Token,
+
+    /// What a running daemon is doing
+    Status,
+
+    /// Ask a running daemon to shut down
+    Stop,
+}
+
 #[derive(Subcommand, Debug)]
 pub enum CompletionsCommand {
     /// Write the completion script where the shell looks for it