test(daemon): drive the whole CLI suite against a daemon, and fix what it caught

SOULSEEK_E2E_MODE=daemon makes the existing e2e harness serve every session
from a daemon instead of the command's own login, so the same 83 tests assert
the same records and exit codes both ways. CI runs the suite twice.

Two defects it found:

serve judged whether anything was shared from this run's configuration
rather than from the session, so routed to a daemon it would start with
nothing to serve and report success.

The TUI showed an empty conversation when attached, because the daemon's
message history was never asked for. It is now a SessionApi method, empty
locally, which puts the difference behind the seam.

main.rs is now a thin entry point over the library rather than a second copy
of every module, so the program compiles once instead of twice.

soulseek-rs/tests/cli_e2e.rs

@@ -98,18 +98,6 @@ fn mode() -> Mode {
     }
 }
 
-/// Skip the rest of a test that has no meaning against a daemon — one about
-/// logging in, or about what happens when a listener port is taken, both of
-/// which are the daemon's business rather than a client's.
-macro_rules! local_only {
-    ($why:expr) => {
-        if mode() == Mode::Daemon {
-            println!("skipped in daemon mode: {}", $why);
-            return;
-        }
-    };
-}
-
 fn run(args: &[&str]) -> Output {
     command(args).output().expect("the binary should run")
 }
@@ -744,12 +732,15 @@ impl TestServer {
         ]
     }
 
-    /// Client arguments pointing at a daemon logged in as `user` with
-    /// `session_flags`, starting one if this combination has not been seen.
+    /// Client arguments pointing at a daemon logged in as `user`, starting one
+    /// if this account has not been seen.
     ///
-    /// Keyed by the flags as well as the user: a test that shares a different
-    /// folder needs a daemon that shares it, and reusing one configured for
-    /// something else would quietly test the wrong thing.
+    /// Strictly one daemon per account: the server allows a single session per
+    /// name, so a second daemon under the same name would displace the first
+    /// and every command already routed to it would start failing with
+    /// "session lost". The session flags of the first call configure it — a
+    /// later call's are ignored, which is exactly what happens in real daemon
+    /// mode, where shares and the listener belong to the daemon.
     fn daemon_args(&self, user: &str, session_flags: &[String]) -> Vec<String> {
         let socket = self.daemon_for(user, session_flags);
         vec![
@@ -761,7 +752,7 @@ impl TestServer {
     }
 
     fn daemon_for(&self, user: &str, session_flags: &[String]) -> PathBuf {
-        let key = format!("{}|{user}|{}", self.address(), session_flags.join(" "));
+        let key = format!("{}|{user}", self.address());
         let mut daemons = self.daemons.lock().expect("daemon registry");
         if let Some(existing) = daemons.get(&key) {
             return existing.socket.clone();