feat(protocol): away status, excluded phrases, queue-place requests

Three features the client half-had. SetStatus (28) was only ever sent as
"online" at login, so there was no way to go away; excluded search phrases
(160) were parsed and logged into nowhere, so every client kept spending
searches on queries the server was never going to answer; and a queued
download could answer a peer asking about its place but could never ask
about its own.

Each is now driven end to end: the away status seen by another user, a
refused query on a stub server that announces phrases (soulfind keeps its
filters in a database the suite cannot seed), and a peer's answer landing
on the download as its queue position.

soulseek-rs-lib/src/message/server/excluded_search_phrases.rs

@@ -12,7 +12,7 @@ impl MessageHandler<ServerMessage> for ExcludedSearchPhrasesHandler {
         160
     }
 
-    fn handle(&self, message: &mut Message, _sender: Sender<ServerMessage>) {
+    fn handle(&self, message: &mut Message, sender: Sender<ServerMessage>) {
         let item_count = message.read_int32();
 
         let mut exluded_phrases: Vec<String> = Vec::new();
@@ -25,6 +25,11 @@ impl MessageHandler<ServerMessage> for ExcludedSearchPhrasesHandler {
             exluded_phrases.push(phrase);
         }
         debug!("Excluded search phrases: {:?}", exluded_phrases);
+        // Kept, not just logged: the server rejects a search carrying one of
+        // these, so a client that forgets them spends its search allowance on
+        // queries that were never going to be answered.
+        let _ =
+            sender.send(ServerMessage::ExcludedSearchPhrases(exluded_phrases));
     }
 }
 
@@ -43,4 +48,22 @@ mod tests {
         });
         ExcludedSearchPhrasesHandler.handle(&mut message, tx);
     }
+
+    #[test]
+    fn the_phrases_are_reported_not_only_logged() {
+        let (tx, rx) = std::sync::mpsc::channel();
+        let mut message = framed(|m| {
+            m.write_int32(2);
+            m.write_string("banned");
+            m.write_string("blocked");
+        });
+
+        ExcludedSearchPhrasesHandler.handle(&mut message, tx);
+        match rx.try_recv() {
+            Ok(ServerMessage::ExcludedSearchPhrases(phrases)) => {
+                assert_eq!(phrases, ["banned", "blocked"]);
+            }
+            other => panic!("unexpected: {other:?}"),
+        }
+    }
 }