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/webrequest.py

@@ -51,14 +51,14 @@ class WebRequest:
         log.info("Using any book")
         return self
 
-    def set_apparat(self, apparat: int):
+    def set_apparat(self, apparat: int) -> "WebRequest":
         self.apparat = apparat
         if int(self.apparat) < 10:
             self.apparat = f"0{self.apparat}"
         log.info(f"Set apparat to {self.apparat}")
         return self
 
-    def get_ppn(self, signature: str):
+    def get_ppn(self, signature: str) -> "WebRequest":
         self.signature = signature
         if "+" in signature:
             signature = signature.replace("+", "%2B")
@@ -90,7 +90,7 @@ class WebRequest:
 
     @sleep_and_retry
     @limits(calls=RATE_LIMIT, period=RATE_PERIOD)
-    def search(self, link: str):
+    def search(self, link: str) -> Optional[str]:
         try:
             response = requests.get(link, timeout=self.timeout)
             return response.text
@@ -98,7 +98,7 @@ class WebRequest:
             log.error(f"Request failed: {e}")
             return None
 
-    def get_data(self) -> Union[list[str], None]:
+    def get_data(self) -> Optional[list[str]]:
         links = self.get_book_links(self.ppn)
         log.debug(f"Links: {links}")
         return_data: list[str] = []
@@ -156,7 +156,7 @@ class WebRequest:
 
         return return_data
 
-    def get_data_elsa(self):
+    def get_data_elsa(self) -> Optional[list[str]]:
         links = self.get_book_links(self.ppn)
         for link in links:
             result = self.search(link)
@@ -197,12 +197,12 @@ class BibTextTransformer:
         self.data = None
         # self.bookdata = BookData(**self.data)
 
-    def use_signature(self, signature: str):
+    def use_signature(self, signature: str) -> "BibTextTransformer":
         """use the exact signature to search for the book"""
         self.signature = signature
         return self
 
-    def get_data(self, data: Union[list[str]] = None) -> "BibTextTransformer":
+    def get_data(self, data: Optional[list[str]] = None) -> "BibTextTransformer":
         RIS_IDENT = "TY  -"
         ARRAY_IDENT = "[kid]"
         COinS_IDENT = "ctx_ver"