Fix core Tokio runtime panic and add network logging

- Fix tokio runtime panic by spawning a dedicated Tokio runtime thread in CoreController.
- Add central log_msg utility in src/lib.rs for debugging.
- Add instrumentation/logs to join, leave, and gossip events in src/network/gossip.rs.
- Add test_net.rs bin for testing gossip loopback sync.
- Use std::sync::Mutex in IrohGossipState to resolve Tokio block-in-async panics.

Cargo.toml

@@ -3,6 +3,18 @@ name = "peerspeak"
 version = "0.1.0"
 edition = "2024"
 
+[lib]
+name = "peerspeak"
+path = "src/lib.rs"
+
+[[bin]]
+name = "peerspeak"
+path = "src/main.rs"
+
+[[bin]]
+name = "test_net"
+path = "src/bin/test_net.rs"
+
 [dependencies]
 anyhow = "1.0.102"
 async-trait = "0.1.89"