Implement remaining code review suggestions

- Add graceful shutdown with SIGTERM/SIGINT handling\n- Make model list configurable via config.yaml\n- Remove sensitive data from debug logs (log sizes instead of full bodies)\n- Handle array format in system messages (both string and []interface{})\n- Update config.yaml with new models structure

main.go

@@ -6,6 +6,9 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"os/signal"
+	"syscall"
+	"time"
 
 	"github.com/google/uuid"
 	"gopkg.in/yaml.v3"
@@ -38,10 +41,28 @@ func main() {
 	})
 
 	addr := fmt.Sprintf(":%d", config.Port)
-	log.Printf("Starting proxx on %s, upstream: %s", addr, config.UpstreamURL)
-	if err := http.ListenAndServe(addr, nil); err != nil {
-		log.Fatalf("Server failed: %v", err)
+	
+	server := &http.Server{Addr: addr}
+	
+	go func() {
+		log.Printf("Starting proxx on %s, upstream: %s", addr, config.UpstreamURL)
+		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			log.Fatalf("Server failed: %v", err)
+		}
+	}()
+	
+	// Wait for interrupt signal
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+	<-sigChan
+	
+	log.Println("Shutting down server...")
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	if err := server.Shutdown(ctx); err != nil {
+		log.Printf("Server shutdown error: %v", err)
 	}
+	log.Println("Server stopped")
 }
 
 // contextKey is a custom type for context keys