feat: add sample multi-user support

feat: update README

client/src/store/index.js

@@ -5,6 +5,7 @@ import messageReducer from './messageSlice.js'
 import modelReducer from './modelSlice.js'
 import submitReducer from './submitSlice.js'
 import textReducer from './textSlice.js'
+import userReducer from './userReducer.js'
 
 export const store = configureStore({
   reducer: {
@@ -13,6 +14,7 @@ export const store = configureStore({
     models: modelReducer,
     text: textReducer,
     submit: submitReducer,
+    user: userReducer,
   },
   devTools: true,
 });

client/src/store/userReducer.js

@@ -0,0 +1,19 @@
+import { createSlice } from '@reduxjs/toolkit';
+
+const initialState = {
+  user: null,
+};
+
+const currentSlice = createSlice({
+  name: 'user',
+  initialState,
+  reducers: {
+    setUser: (state, action) => {
+      state.user = action.payload;
+    },
+  }
+});
+
+export const { setUser } = currentSlice.actions;
+
+export default currentSlice.reducer;