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/ui/widgets/filepicker.py

@@ -21,7 +21,7 @@ class FilePicker:
         files, _ = filepicker.getOpenFileNames(
             caption="Open file",
             dir=self.last_path,
-            filter="Unterstützte Dateien (*.docx *.csv *.eml );;Word (*.docx);;CSV Files (*.csv);;Mail (*.eml)",
+            filter="Unterstützte Dateien (*.docx *.doc *.csv *.eml );;Word (*.docx *.doc);;CSV Files (*.csv);;Mail (*.eml)",
         )
         if files:
             self.last_path = files[0]