add postgres and refactor code

pkg/utils/type-coverter.go

@@ -0,0 +1,16 @@
+package utils
+
+import "encoding/json"
+
+func TypeConverter[R any](data any) (*R, error) {
+	var result R
+	b, err := json.Marshal(&data)
+	if err != nil {
+		return nil, err
+	}
+	err = json.Unmarshal(b, &result)
+	if err != nil {
+		return nil, err
+	}
+	return &result, err
+}