Implement Network Transport Layer for Validator Communication

[thcsomebody]

Implement the initial network transport layer for consensus validators, as outlined in the project instructions:

• Integrate with the lib-network crate for P2P messaging and validator connections.
• Create a ConsensusNetwork struct to handle peer communication between validators.
• Implement message serialization/deserialization for consensus messages.
• Scaffold methods for sending and receiving proposals, votes, and general network messages to/from peers.
• Ensure easy future expansion for DHT peer discovery, broadcasting, and connection pooling.

Acceptance Criteria:

• A new module or file for the network transport layer is added (e.g., network.rs).
• ConsensusNetwork struct manages connections and message passing between validators.
• Consensus messages (proposals, votes, etc.) can be serialized and deserialized for network transport.
• No-op or stub methods for future DHT/discovery/broadcasting are present.
• All code compiles and passes cargo check.

Refer to the project instructions: "Add Network Transport Layer" and "Integrate with lib-network for P2P messaging".