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/client/operations.rs

@@ -816,6 +816,11 @@ impl Client {
                             ctx.apply_user_interests(interests);
                         }
                     }
+                    ClientOperation::ExcludedSearchPhrases(phrases) => {
+                        if let Ok(mut ctx) = client_context.write_safe() {
+                            ctx.set_excluded_search_phrases(phrases);
+                        }
+                    }
                     ClientOperation::CantConnectToPeer { token } => {
                         // The peer we asked the server to broker gave up. The
                         // token is the correlation we sent, so it names the