Store setting in localStorage to retain across refresh (#42)

* Store setting in localStorage to retain across refresh

Set the value of the darkMode setting in localStorage using hooks when the
value changes. Also, added functionality to read the stored value when the
settings load when the app loads

src/app.js

@@ -52,7 +52,6 @@ const App = () => {
         })
     }
 
-    // TODO: Store mode in local storage per user
     const theme = useMemo(() => createTheme(getTheme()), [isDarkMode]);
 
     return (

src/features/app/appSlice.js

@@ -1,6 +1,10 @@
 import { createSlice } from "@reduxjs/toolkit"
 import { apiSlice } from "../api/apiSlice"
 
+const storageNames = {
+    darkMode: 'darkMode'
+}
+
 const appSlice = createSlice({
     name: 'app',
     initialState: {
@@ -17,8 +21,12 @@ const appSlice = createSlice({
         }
     },
     extraReducers(builder) {
+        builder.addMatcher(appSlice.actions.toggleDarkMode.match, (state) => {
+            localStorage.setItem(storageNames.darkMode, state.darkMode)
+        })
         builder.addMatcher(apiSlice.endpoints.getSettings.matchFulfilled, (state, { payload }) => {
             state.authDisabled = payload.authDisabled
+            state.darkMode = localStorage.getItem(storageNames.darkMode)
         })
     }
 })