feat(p2p): mesh stack, LoRa mock transport, and relay demo

Implement transport abstraction (TCP/iroh), announce and routing table,
multi-hop mesh router, truncated-address link layer, and LoRa mock
medium with fragmentation plus EU868-style duty-cycle accounting.
Add mesh_lora_relay_demo and scripts/mesh-demo.sh. Relax CBOR vs JSON
size assertion to match fixed-size cryptographic overhead. Extend
.gitignore for nested targets and node_modules.

Made-with: Cursor

crates/quicprochat-p2p/src/lib.rs

@@ -12,11 +12,22 @@
 //!     └── QUIC/TLS ── Server ── QUIC/TLS ┘  (fallback: store-and-forward)
 //! ```
 
+pub mod address;
+pub mod announce;
+pub mod announce_protocol;
 pub mod broadcast;
 pub mod envelope;
 pub mod identity;
+pub mod link;
+pub mod mesh_router;
 pub mod routing;
+pub mod routing_table;
 pub mod store;
+pub mod transport;
+pub mod transport_iroh;
+pub mod transport_manager;
+pub mod transport_tcp;
+pub mod transport_lora;
 #[cfg(feature = "traffic-resistance")]
 pub mod traffic_resistance;
 
@@ -204,7 +215,7 @@ impl P2pNode {
             .ok_or_else(|| anyhow::anyhow!("mesh identity not configured"))?;
 
         let envelope = MeshEnvelope::new(identity, recipient_key, payload, ttl_secs, 0);
-        let bytes = envelope.to_bytes();
+        let bytes = envelope.to_wire();
 
         if let Some(addr) = peer_addr {
             self.send(addr, &bytes).await?;
@@ -257,7 +268,7 @@ impl P2pNode {
         for env in envelopes {
             if env.can_forward() {
                 let fwd = env.forwarded();
-                let bytes = fwd.to_bytes();
+                let bytes = fwd.to_wire();
                 self.send(peer_addr.clone(), &bytes).await?;
                 forwarded += 1;
             }
@@ -318,7 +329,7 @@ impl P2pNode {
 
         // Create a broadcast envelope (empty recipient_key signals broadcast).
         let envelope = MeshEnvelope::new(identity, &[], encrypted, 300, 0);
-        let bytes = envelope.to_bytes();
+        let bytes = envelope.to_wire();
 
         // Store in the mesh store for flood-forwarding.
         let mut store = self