feat(redux): Rename all Redux slices and store keys to match file names for clarity

- Renamed all slice names (createSlice `name` attribute) to match their file names (e.g. loopChartSlice, authSlice, kueDataSlice etc.)
- Updated `store.ts` to register each reducer with consistent key names (e.g. state.loopChartSlice instead of state.loopChart)
- Adjusted all `useSelector` and Redux state accesses across the codebase
- Improves maintainability, searchability and consistency across files and Redux DevTools

components/main/uebersicht/Last20MessagesTable.tsx

@@ -9,7 +9,7 @@ const Last20MessagesTable: React.FC = () => {
 
   // Holt last20Messages aus Redux
   const rawLast20Messages = useSelector(
-    (state: RootState) => state.last20Messages.last20Messages
+    (state: RootState) => state.last20MessagesSlice.last20Messages
   );
 
   // Holt Daten aus `window.win_last20Messages` und speichert sie in Redux