feat(tui): implement agent turn engine for background processing and enhance input handling

apps/infrastructure/src/llm/provider.rs

@@ -240,7 +240,9 @@ impl LlmClient {
                     StreamEvent::Token(_) | StreamEvent::Reasoning(_) => {
                         captured_content = true;
                     }
-                    _ => {}
+                    _ => {
+                        tracing::debug!("unhandled stream event type in wrapped closure");
+                    }
                 }
                 on_event(event)
             };
@@ -373,7 +375,9 @@ impl LlmClient {
                             );
                         }
                     }
-                    _ => {}
+                    _ => {
+                        tracing::debug!("unhandled stream event in apply_event: {event:?}");
+                    }
                 }
             }
 
@@ -441,7 +445,10 @@ impl LlmClient {
                         turn.done_received = true;
                         return Ok((turn.build_assistant_message(), usage));
                     }
-                    _ => turn.apply_event(&event),
+                    other => {
+                        tracing::debug!("unhandled stream event type: {other:?}");
+                        turn.apply_event(other);
+                    }
                 }
             }
         }