bxctl: chat --speaker NAME, the speaker on every turn of the chat

Co-Authored-By: ornith-1.5-35b-a3b <agent@wntrmute.dev>

crates/bxctl/tests/chat.rs

@@ -161,6 +161,7 @@ fn run_turn_delivers_every_event_in_order_then_the_answer() {
         &id("s1"),
         "what time is it?",
         false,
+        None,
         &mut |e| seen.push(e.clone()),
     )
     .unwrap();
@@ -189,7 +190,7 @@ fn an_error_frame_is_refused_with_its_code_and_detail() {
         End::Error(ErrorCode::SessionFull, "this conversation is full"),
     );
     let mut seen = 0;
-    let err = run_turn(&fake.socket, &id("s1"), "x", true, &mut |_| seen += 1).unwrap_err();
+    let err = run_turn(&fake.socket, &id("s1"), "x", true, None, &mut |_| seen += 1).unwrap_err();
     assert_eq!(seen, 1, "events before the error are still delivered");
     match err {
         ChatError::Refused(w) => {
@@ -199,7 +200,7 @@ fn an_error_frame_is_refused_with_its_code_and_detail() {
         other => panic!("{other:?}"),
     }
     let e: Box<dyn std::error::Error> =
-        Box::new(run_turn(&fake.socket, &id("s1"), "x", true, &mut |_| {}).unwrap_err());
+        Box::new(run_turn(&fake.socket, &id("s1"), "x", true, None, &mut |_| {}).unwrap_err());
     assert!(e.to_string().contains("session full"), "{e}");
 }
 
@@ -207,7 +208,7 @@ fn an_error_frame_is_refused_with_its_code_and_detail() {
 fn no_loopd_is_a_connect_error() {
     let missing = std::env::temp_dir().join("bxctl-no-such-loopd.sock");
     assert!(matches!(
-        run_turn(&missing, &id("s1"), "x", false, &mut |_| {}),
+        run_turn(&missing, &id("s1"), "x", false, None, &mut |_| {}),
         Err(ChatError::Connect(_))
     ));
 }