REFACTOR(repo): simplify project structure

- Move services/nextjs to nextjs/
- Move deploy/docker/Dockerfile.prod to Dockerfile
- Add GitHub Actions workflows (ci.yml, build.yml)
- Remove deploy/, services/, scripts/ folders

nextjs/src/entities/user/model/store.ts

@@ -0,0 +1,13 @@
+import { create } from 'zustand';
+import { UserState, UserActions, User } from './types';
+
+// User state management store
+export const useUserStore = create<UserState & UserActions>((set) => ({
+  user: null,
+  isLoading: true,
+
+  setUser: (user: User | null) => set({ user }),
+
+  setLoading: (isLoading: boolean) => set({ isLoading }),
+}));
+