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/backend/database.py

@@ -144,7 +144,7 @@ class Database:
             self.create_tables()
             self.insertSubjects()
 
-    def getElsaMediaID(self, work_author, signature, pages):
+    def getElsaMediaID(self, work_author: str, signature: str, pages: str):
         query = (
             "SELECT id FROM elsa_media WHERE work_author=? AND signature=? AND pages=?"
         )
@@ -160,7 +160,7 @@ class Database:
         query = "SELECT type FROM elsa_media WHERE id=?"
         return self.query_db(query, (id,), one=True)[0]
 
-    def get_db_contents(self) -> Union[List[Tuple], None]:
+    def get_db_contents(self) -> Union[List[Tuple[Any]], None]:
         """
         Get the contents of the