feat: add rust-p2p skill

[iamquang95]

This add skill to help agents implement and review rust libp2p related package

[varex83]

LGTM!

[emlautarom1]

This paragraph is not very clear (why conn_logger? Write what specifically? Is this a matter of ordering?)

[iamquang95]

The conn_logger is a core behaviour in PlutoBehaviour. The peer_store in p2p_context is updated by conn_logger, and other behaviours use that peer_store.

/// Pluto network behaviour.
///
/// Combines multiple libp2p protocols:
/// - **Connection logging**: Tracks connections and updates peer store (first
///   to ensure other behaviours see updated peer state)
/// - **Connection gating**: Controls which connections are allowed
/// - **Identify**: Exchanges peer information and supported protocols
/// - **Ping**: Measures latency and keeps connections alive
/// - **AutoNAT**: Detects NAT status and public reachability
/// - **QUIC upgrade**: Periodically upgrades TCP connections to QUIC
#[derive(NetworkBehaviour)]
pub struct PlutoBehaviour<B: NetworkBehaviour> {
    /// Connection logger behaviour - MUST be first so peer store is updated
    /// before other behaviours process connection events.
    pub conn_logger: ConnectionLoggerBehaviour<DefaultConnectionLoggerMetrics>,
    /// Connection gater behaviour.
    pub gater: ConnGater,
    /// Identify behaviour.
    pub identify: identify::Behaviour,
    /// Ping behaviour.
    pub ping: ping::Behaviour,
    /// AutoNAT behaviour for NAT detection.
    pub autonat: autonat::Behaviour,
    /// QUIC upgrade behaviour for upgrading TCP to QUIC connections.
    pub quic_upgrade: QuicUpgradeBehaviour,
    /// Inner behaviour.
    pub inner: OptionalBehaviour<B>,
}

Ordering matters because #[derive(NetworkBehaviour)] delegates each trait method to fields in struct order. For poll(), it polls first field until Pending, then next field. That's why the conn_logger has to be placed on the top in PlutoBehaviour.

[emlautarom1]

Does libp2p have any skills on the topic? Maybe we could incorporate them if so.

[iamquang95]

I couldn't find any skill related to rust-libp2p. Later if we can find some, we can improve our skill.