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

apps/infrastructure/src/auth/oauth_loopback.rs

@@ -55,8 +55,12 @@ impl LoopbackServer {
                  Missing authorization code."
             }
         };
-        let _ = stream.write_all(response.as_bytes());
-        let _ = stream.flush();
+        if let Err(e) = stream.write_all(response.as_bytes()) {
+            tracing::warn!("OAuth loopback write error: {e}");
+        }
+        if let Err(e) = stream.flush() {
+            tracing::warn!("OAuth loopback flush error: {e}");
+        }
         if !state_ok {
             return Err(std::io::Error::new(
                 std::io::ErrorKind::InvalidData,