🐛 fix(__main__.py): change word variable from "LangFlow" to "Langflow" for consistency

🐛 fix(schemas.py): change class name from "ExportedFlow" to "Exported flow from Langflow" for consistency
The word variable in __main__.py is changed from "LangFlow" to "Langflow" to maintain consistency in naming conventions. Similarly, the class name in schemas.py is changed from "ExportedFlow" to "Exported flow from Langflow" for consistency in naming conventions.