## What changed
- Add a `NoiseStreamHandler` abstraction that owns payload encoding, decoding,
and connection processing while the virtual stream handles framing,
encryption, and multiplexing.
- Reassemble authenticated payloads as opaque bytes, with the existing
JSON-RPC processor supplied as a handler implementation.
- Have the physical relay send a reset after the current stream instance
closes, including when its processor exits before the writer task.
## Testing
- Verify local JSON-RPC decoding creates the queued request span before queue
admission.
- Verify a processor exit resets the corresponding Noise harness stream.
GitOrigin-RevId: 270befcc8bfbf27e46c84d6a2c6e349cb98ea3f8
