add redux and user slice

frontend/src/shared/domain-models/userSlice.ts

@@ -0,0 +1,31 @@
+import { createSlice } from '@reduxjs/toolkit'
+
+type LoadingState = "not-started" | "loading" | "finished"
+
+export const userSlice = createSlice({
+    name: 'user',
+    initialState: {
+        state: "not-started" as LoadingState,
+        email: null,
+    },
+    reducers: {
+        load: (state) => {
+            state.state = "loading"
+        },
+        setUser: (state, action) => {
+            state.state = "finished"
+            state.email = action.payload
+        },
+        unsetUser: (state) => {
+            state.state = "finished"
+            state.email = null
+        }
+    },
+})
+
+// Action creators are generated for each case reducer function
+export const { load, setUser, unsetUser } = userSlice.actions
+
+export const userSelector = userSlice.selectSlice
+
+export default userSlice.reducer