refactor: call database functions from app.Server.Database instead of directly from db

routes/admin/routes.go

@@ -0,0 +1,12 @@
+package admin
+
+import "net/http"
+
+func SetupRoutes() *http.ServeMux {
+	handler := http.NewServeMux()
+	handler.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("Hello, World!"))
+		return
+	})
+	return handler
+}