Function route_stream_frame 

pub fn route_stream_frame(
    value_json: &str,
    handlers: &Arc<Mutex<HashMap<String, BreakpointStreamFrameHandler>>>,
) -> Option<(String, StreamFrameDecision)>

Route a stream-frame message: dispatch to the per-breakpoint-id handler, auto-continue on missing handler or panic. Returns (type_name, decision).