⭐ feat: Migrate from WebSocket to libp2p for peer-to-peer connectivity (#286)

## Description
Whew, some stuff is still not re-implemented, but it's working!

Rabbit's gonna explode with the amount of changes I reckon 😅



<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **New Features**
- Introduced a peer-to-peer relay system using libp2p with enhanced
stream forwarding, room state synchronization, and mDNS peer discovery.
- Added decentralized room and participant management, metrics
publishing, and safe, size-limited, concurrent message streaming with
robust framing and callback dispatching.
- Implemented asynchronous, callback-driven message handling over custom
libp2p streams replacing WebSocket signaling.
- **Improvements**
- Migrated signaling and stream protocols from WebSocket to libp2p,
improving reliability and scalability.
- Simplified configuration and environment variables, removing
deprecated flags and adding persistent data support.
- Enhanced logging, error handling, and connection management for better
observability and robustness.
- Refined RTP header extension registration and NAT IP handling for
improved WebRTC performance.
- **Bug Fixes**
- Improved ICE candidate buffering and SDP negotiation in WebRTC
connections.
  - Fixed NAT IP and UDP port range configuration issues.
- **Refactor**
- Modularized codebase, reorganized relay and server logic, and removed
deprecated WebSocket-based components.
- Streamlined message structures, removed obsolete enums and message
types, and simplified SafeMap concurrency.
- Replaced WebSocket signaling with libp2p stream protocols in server
and relay components.
- **Chores**
- Updated and cleaned dependencies across Go, Rust, and JavaScript
packages.
  - Added `.gitignore` for persistent data directory in relay package.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: DatCaptainHorse <DatCaptainHorse@users.noreply.github.com>
Co-authored-by: Philipp Neumann <3daquawolf@gmail.com>

packages/server/src/p2p/p2p.rs

@@ -0,0 +1,131 @@
+use futures_util::StreamExt;
+use libp2p::multiaddr::Protocol;
+use libp2p::{
+    Multiaddr, PeerId, Swarm, identify, noise, ping,
+    swarm::{NetworkBehaviour, SwarmEvent},
+    tcp, yamux,
+};
+use std::error::Error;
+use std::sync::Arc;
+use tokio::sync::Mutex;
+
+#[derive(Clone)]
+pub struct NestriConnection {
+    pub peer_id: PeerId,
+    pub control: libp2p_stream::Control,
+}
+
+#[derive(NetworkBehaviour)]
+struct NestriBehaviour {
+    identify: identify::Behaviour,
+    ping: ping::Behaviour,
+    stream: libp2p_stream::Behaviour,
+}
+
+pub struct NestriP2P {
+    swarm: Arc<Mutex<Swarm<NestriBehaviour>>>,
+}
+impl NestriP2P {
+    pub async fn new() -> Result<Self, Box<dyn Error>> {
+        let swarm = Arc::new(Mutex::new(
+            libp2p::SwarmBuilder::with_new_identity()
+                .with_tokio()
+                .with_tcp(
+                    tcp::Config::default(),
+                    noise::Config::new,
+                    yamux::Config::default,
+                )?
+                .with_dns()?
+                .with_behaviour(|key| {
+                    let identify_behaviour = identify::Behaviour::new(identify::Config::new(
+                        "/ipfs/id/1.0.0".to_string(),
+                        key.public(),
+                    ));
+                    let ping_behaviour = ping::Behaviour::default();
+                    let stream_behaviour = libp2p_stream::Behaviour::default();
+
+                    Ok(NestriBehaviour {
+                        identify: identify_behaviour,
+                        ping: ping_behaviour,
+                        stream: stream_behaviour,
+                    })
+                })?
+                .build(),
+        ));
+
+        // Spawn the swarm event loop
+        let swarm_clone = swarm.clone();
+        tokio::spawn(swarm_loop(swarm_clone));
+
+        {
+            let mut swarm_lock = swarm.lock().await;
+            swarm_lock.listen_on("/ip4/0.0.0.0/tcp/0".parse()?)?; // IPv4 - TCP Raw
+            swarm_lock.listen_on("/ip6/::/tcp/0".parse()?)?; // IPv6 - TCP Raw
+        }
+
+        Ok(NestriP2P { swarm })
+    }
+
+    pub async fn connect(&self, conn_url: &str) -> Result<NestriConnection, Box<dyn Error>> {
+        let conn_addr: Multiaddr = conn_url.parse()?;
+
+        let mut swarm_lock = self.swarm.lock().await;
+        swarm_lock.dial(conn_addr.clone())?;
+
+        let Some(Protocol::P2p(peer_id)) = conn_addr.clone().iter().last() else {
+            return Err("Invalid connection URL: missing peer ID".into());
+        };
+
+        Ok(NestriConnection {
+            peer_id,
+            control: swarm_lock.behaviour().stream.new_control(),
+        })
+    }
+}
+
+async fn swarm_loop(swarm: Arc<Mutex<Swarm<NestriBehaviour>>>) {
+    loop {
+        let event = {
+            let mut swarm_lock = swarm.lock().await;
+            swarm_lock.select_next_some().await
+        };
+        match event {
+            SwarmEvent::NewListenAddr { address, .. } => {
+                tracing::info!("Listening on: '{}'", address);
+            }
+            SwarmEvent::ConnectionEstablished { peer_id, .. } => {
+                tracing::info!("Connection established with peer: {}", peer_id);
+            }
+            SwarmEvent::ConnectionClosed { peer_id, cause, .. } => {
+                if let Some(err) = cause {
+                    tracing::error!(
+                        "Connection with peer {} closed due to error: {}",
+                        peer_id,
+                        err
+                    );
+                } else {
+                    tracing::info!("Connection with peer {} closed", peer_id);
+                }
+            }
+            SwarmEvent::IncomingConnection {
+                local_addr,
+                send_back_addr,
+                ..
+            } => {
+                tracing::info!(
+                    "Incoming connection from: {} (send back to: {})",
+                    local_addr,
+                    send_back_addr
+                );
+            }
+            SwarmEvent::OutgoingConnectionError { peer_id, error, .. } => {
+                if let Some(peer_id) = peer_id {
+                    tracing::error!("Failed to connect to peer {}: {}", peer_id, error);
+                } else {
+                    tracing::error!("Failed to connect: {}", error);
+                }
+            }
+            _ => {}
+        }
+    }
+}