bug: ChromeRuntimeDuplexStream fails when multiple streams share the same target #214
Description
When creating multiple ChromeRuntimeDuplexStream instances, the same endpoint (e.g., offscreen) can be both a localTarget in one connection and a remoteTarget in another. This causes issues when, for example, creating a stream between background and offscreen, and then another between devtools and offscreen. The second stream fails with the error "ChromeRuntimeReader received message for unexpected target" because the offscreen endpoint is trying to act as both a local and remote target.