refactor(gui): ✨ Improve filter handling in MainWindow

* Refactored the filter extraction logic to directly use `header.filter_text(i)` for better clarity.
* Updated the filters list to store tuples of index and text, enhancing the data structure used.
* Ensured that the `proxy_model.filters` is set directly, simplifying the code.

tidal_dl_ng/gui.py

@@ -328,10 +328,12 @@ class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
         header = self.tr_results.header()
         filters: list[str] = []
         for i in range(header.count()):
-            # Use getattr to avoid attribute error
-            filters.append(getattr(header, "filter_text", lambda x: "")(i))
-        proxy_model = self.tr_results.model()
-        if hasattr(proxy_model, "filters"):
+            text: str = header.filter_text(i)
+
+            if text:
+                filters.append((i, text))
+
+        proxy_model: HumanProxyModel = self.tr_results.model()
         proxy_model.filters = filters
 
     def _init_tree_results(self, tree: QtWidgets.QTreeView, model: QtGui.QStandardItemModel) -> None: