Add request tracing, debug /v1/keys/list endpoint

- TraceLayer logs every HTTP request (method, path, status, duration)
- Default log level info, tower_http=debug (no RUST_LOG needed)
- GET /v1/keys/list shows all registered fingerprints
- Helps debug key registration and lookup issues

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

warzone/crates/warzone-server/src/main.rs

@@ -20,7 +20,12 @@ struct Cli {
 
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
-    tracing_subscriber::fmt::init();
+    tracing_subscriber::fmt()
+        .with_env_filter(
+            tracing_subscriber::EnvFilter::try_from_default_env()
+                .unwrap_or_else(|_| "info,tower_http=debug".parse().unwrap()),
+        )
+        .init();
 
     let cli = Cli::parse();
     tracing::info!("Warzone server starting on {}", cli.bind);
@@ -30,6 +35,7 @@ async fn main() -> anyhow::Result<()> {
     let app = axum::Router::new()
         .merge(routes::web_router())
         .nest("/v1", routes::router())
+        .layer(tower_http::trace::TraceLayer::new_for_http())
         .with_state(state);
 
     let listener = tokio::net::TcpListener::bind(&cli.bind).await?;