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/header/Header.tsx

@@ -54,7 +54,7 @@ function Header() {
   const dispatch = useDispatch<AppDispatch>();
 
   const deviceName = useSelector(
-    (state: RootState) => state.systemSettings.deviceName
+    (state: RootState) => state.systemSettingsSlice.deviceName
   );
 
   useEffect(() => {