Description

1. NAT Traversal and Hole Punching

• Adds a new HolePunchService implementing the /libp2p/holepunch/1.0.0 protocol.
• Lays the groundwork for advanced NAT traversal, enabling peers behind NATs to establish direct connections using coordinated hole punching.
• The service is ready for integration with AutoNAT and relay-based coordination.

2. Relay v2 Upgrades

• Implements client-side reservation storage and automatic renewal in CircuitV2Transport, ensuring relay reservations are refreshed before expiration.
• Adds support for multi-hop relays, allowing connections to be established through a chain of relay nodes when direct or single-hop relay connections are not possible.
• Updates relay selection and dialing logic to handle multi-hop relay addresses.