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/logic/pdfparser.py

@@ -1,10 +1,9 @@
 # add depend path to system path
 
-import pandas as pd
 from pdfquery import PDFQuery
 
 
-def pdf_to_csv(path: str) -> pd.DataFrame:
+def pdf_to_csv(path: str) -> str:
     """
     Extracts the data from a pdf file and returns it as a pandas dataframe
     """