Feat: implement client side functionality for user follow feature

src/requests/UserFollow/sendUserFollowRequest.ts

@@ -0,0 +1,16 @@
+import APIResponseValidationSchema from '@/validation/APIResponseValidationSchema';
+
+const sendUserFollowRequest = async (userId: string) => {
+  const response = await fetch(`/api/users/${userId}/follow-user`, { method: 'POST' });
+  const json = await response.json();
+
+  const parsed = APIResponseValidationSchema.safeParse(json);
+
+  if (!parsed.success) {
+    throw new Error('Invalid API response.');
+  }
+
+  return parsed;
+};
+
+export default sendUserFollowRequest;