useMutation is used for operations that create, update, or delete data (side effects). Unlike useQuery, mutations don't run automatically and must be triggered manually.
Basic usage:

const mutation = useMutation({
  mutationFn: (newPost) => fetch('/api/posts', {
    method: 'POST',
    body: JSON.stringify(newPost)
  }),
  onSuccess: (data) => {
    // Invalidate and refetch related queries
    queryClient.invalidateQueries({ queryKey: ['posts'] });
  },
  onError: (error) => {
    console.error('Failed to create post:', error);
  }
});
// Trigger the mutation
const handleSubmit = (formData) => {
  mutation.mutate(formData);
};

Key properties:

• mutationFn: Function that performs the mutation
• onSuccess: Callback for successful mutations
• onError: Callback for failed mutations
• onSettled: Callback that runs regardless of success/failure
  Use cases:
• Creating new records
• Updating existing data
• Deleting records
• Any operation that modifies server state