feat(p2p): add connection logging behaviour and global peer context

[varex83]

This PR implements connection logging behaviour

Summary

This PR introduces connection logging functionality to the P2P module, porting the connection logging behaviour from Charon Go. The implementation tracks and logs libp2p connection lifecycle events while exposing connection metrics.

Key Changes

• Connection Logger Behaviour (conn_logger.rs): A new NetworkBehaviour implementation that:

  • Tracks inbound/outbound connections per peer with connection type (direct/relay) and protocol (TCP/QUIC) granularity
  • Emits structured tracing logs for connection establishment and closure events
  • Exposes metrics via a pluggable ConnectionLoggerMetrics trait with default and test implementations
  • Includes comprehensive unit tests for connection counting logic
  • Add ping latencies and other metrics.

• Global Context (global_context.rs): Introduces a shared GlobalContext with a thread-safe PeerStore for tracking active/inactive peers across the P2P stack

• Optional Behaviour Wrapper (optional.rs): A generic OptionalBehaviour<B> wrapper that allows behaviours to be conditionally enabled, simplifying behaviour composition

• Pluto Behaviour Refactoring:

  • Simplified PlutoBehaviour to use OptionalBehaviour for the inner behaviour
  • Removed custom dummy connection handler in favour of libp2p's built-in implementation
  • Added GlobalContext integration to the behaviour builder

• Node API Improvements:

  • Node now implements Stream for ergonomic event handling
  • Added GlobalContext propagation through node creation
  • Closure signatures updated to receive GlobalContext for inner behaviour construction

• Utility Additions: Helper functions for detecting relay addresses (is_relay_addr) and QUIC addresses (is_quic_addr), plus connection type/protocol classification

Test Plan

• Verify connection logger metrics are correctly incremented/decremented during peer connections
• Run the p2p.rs example with multiple nodes to validate mDNS discovery and relay connections
• Confirm structured logs appear with correct peer names and connection metadata
• Review metrics output via the metrics endpoint

[emlautarom1]

There are multiple points in this PR:

• The move to Stream for p2p behaviors.
• The refactoring of how we construct nodes and relay servers
• Connection logging

Overall looks good, but it would have been better to have it as stacked PRs.

The only issue that I see is on the refactoring where the code for constructing nodes and relays is quite convoluted and could use some improvements.

Some tests seem excessive (most likely AI generating for the sake of it) and I expect that we can trim them down with some minor changes.

[emlautarom1]

LGTM. We'll revisit the constructor code later, for now no need to worry about it.

[iamquang95]

LGTM!