Refactor and enhance type hints across multiple modules

- Updated the `from_tuple` method in `Prof` class to specify return type.
- Added type hints for various methods in `LehmannsClient`, `OpenAI`, `WebRequest`, and `ZoteroController` classes to improve code clarity and type safety.
- Modified `pdf_to_csv` function to return a string instead of a DataFrame.
- Enhanced error handling and type hints in `wordparser` and `xmlparser` modules.
- Removed unused UI file `Ui_medianadder.ts`.
- Improved the layout and structure of the `semesterapparat_ui` to enhance user experience.
- Updated file picker to support `.doc` files in addition to `.docx`.
- Added unique item handling in `Ui` class to prevent duplicates in apparat list.
- General code cleanup and consistency improvements across various files.

src/__init__.py

@@ -3,6 +3,8 @@ __author__ = "Alexander Kirchner"
 __all__ = ["__version__", "__author__", "Icon", "settings"]
 
 import os
+from pathlib import Path
+from typing import Union
 
 from appdirs import AppDirs
 
@@ -18,7 +20,7 @@ if not os.path.exists(CONFIG_DIR):  # type: ignore
 
 
 settings = Config(f"{CONFIG_DIR}/config.yaml")
-DATABASE_DIR = (  # type: ignore
+DATABASE_DIR: Union[Path, str] = (  # type: ignore
     app.user_config_dir if settings.database.path is None else settings.database.path  # type: ignore
 )
 if not os.path.exists(DATABASE_DIR):  # type: ignore