feat(chat-server): implement graceful shutdown with OS signal handling

veza-chat-server/src/main.rs

@@ -304,6 +304,7 @@ async fn main() -> Result<(), ChatError> {
     info!("   - GET  /ws              - WebSocket Chat (🆕)");
 
     axum::serve(listener, app)
+        .with_graceful_shutdown(shutdown_signal())
         .await
         .map_err(|e| ChatError::configuration_error(&format!("Server error: {e}")))?;
 
@@ -447,3 +448,30 @@ async fn get_stats(State(_state): State<AppState>) -> Json<ApiResponse<HashMap<S
 
     Json(ApiResponse::success(stats))
 }
+
+/// Gestionnaire de signal d'arrêt (Graceful Shutdown)
+async fn shutdown_signal() {
+    let ctrl_c = async {
+        tokio::signal::ctrl_c()
+            .await
+            .expect("failed to install Ctrl+C handler");
+    };
+
+    #[cfg(unix)]
+    let terminate = async {
+        tokio::signal::unix::signal(tokio::signal::unix::SignalKind::terminate())
+            .expect("failed to install signal handler")
+            .recv()
+            .await;
+    };
+
+    #[cfg(not(unix))]
+    let terminate = std::future::pending::<()>();
+
+    tokio::select! {
+        _ = ctrl_c => {},
+        _ = terminate => {},
+    }
+    
+    info!("🛑 Signal d'arrêt reçu, fermeture gracieuse...");
+}