Bug: You can vote multiple times as the same user

[wasdJens]

Describe the bug

• You can cast multiple votes in the same poll as the same user.
• When refreshing the page you can vote again in a poll.

To Reproduce Create a poll. Vote once. Use the browser to refresh the page. Repeat

Expected behavior To not mess up poll results users should only be allowed to vote once in a poll. After voting you should store the voted users id in the server.

Screenshots If applicable, add screenshots to help explain your problem.

Additional context Add any other context about the problem here.

[DevPhilB]

Fix in PR #260 doesn't include any additional UI feedback, he can still click on the vote button but his vote doesn't count (is refused by the server).

[wasdJens]

he can still click on the vote button but his vote doesn't count (is refused by the server).

If possible direclty show the result page if the user has already voted