Add zustand, true-myth, primitive authentication state, startup getSession()

frontend/src/lib/state.ts

@@ -0,0 +1,19 @@
+import { create } from "zustand";
+
+type UserState = {
+  user: {
+    // TODO: This will eventually carry more user information (name, avatar, etc.)
+    email: string;
+  } | null;
+};
+
+type UserActions = {
+  setUser: (user: UserState["user"]) => void;
+  logout: () => void;
+};
+
+export const useUserStore = create<UserState & UserActions>((set) => ({
+  user: null,
+  setUser: (user) => set({ user }),
+  logout: () => set({ user: null }),
+}));