feat(feed): implement ScrobbleSubscriber for handling WebSocket messages
- Added a new `ScrobbleSubscriber` struct to manage WebSocket connections and message handling.
- Integrated `ScrobbleSubscriber` into the feed server to listen for messages from the Jetstream server.
- Updated `Cargo.toml` to include dependencies for `tokio-tungstenite` and `tungstenite`.
- Introduced new types in `types.rs` for handling incoming messages.
- Refactored existing subscriber logic in the `jetstream` crate to align with the new structure.