feat: make header components atomic & remove unused menu

apps/landing/src/stores/mobile-menu-store.ts

@@ -0,0 +1,12 @@
+import { create } from 'zustand';
+
+interface MobileMenuState {
+  mobileMenuOpen: boolean;
+  toggleMobileMenu: () => void;
+}
+
+export const useMobileMenuStore = create<MobileMenuState>((set) => ({
+  mobileMenuOpen: false,
+  toggleMobileMenu: () =>
+    set((state) => ({ mobileMenuOpen: !state.mobileMenuOpen })),
+}));