feat(fields): enhance encryption in JSONField with direct processing

Replace parent method call in `get_prep_value` with direct encryption logic to prevent errors caused by incorrect JSON parsing. This ensures the proper handling of JSON strings and avoids reliance on parent class behavior.

schon/fields.py

@@ -21,9 +21,17 @@ class EncryptedJSONTextField(EncryptedTextField):
         return super().formfield(**{"form_class": forms.JSONField, **kwargs})
 
     def get_prep_value(self, value):
-        if value is not None and not isinstance(value, str):
+        # Encrypt directly instead of delegating to super().get_prep_value().
+        # The parent chain (EncryptedFieldMixin → CharField) calls
+        # self.to_python() which parses the JSON string back to a dict,
+        # then str(dict) produces Python repr with single quotes — not JSON.
+        if value is None:
+            return None
+        if not isinstance(value, str):
             value = orjson.dumps(value, default=str).decode("utf-8")
-        return super().get_prep_value(value)
+        if not value:
+            return None
+        return self.f.encrypt(value.encode("utf-8")).decode("utf-8")
 
     def from_db_value(self, value, expression, connection):
         if value is None: