feat(navbar): add modular navbar components and color variables

apps/web/src/components/navbar/NavLogin.tsx

@@ -0,0 +1,17 @@
+import { Link } from "@tanstack/react-router";
+
+const NavLogin = () => {
+  return (
+    <Link
+      to="/login"
+      className="text-sm font-medium px-4 py-1.5 rounded-full
+        text-white bg-(--color-primary)
+        hover:bg-(--color-primary-dark)
+        transition-colors duration-200"
+    >
+      Sign in
+    </Link>
+  );
+};
+
+export default NavLogin;