Bug(frontend): check if user already transitioned before upvote/downvote -ing

[kittybest]

Describe the bug
If the user's currentEpoch does not match the contract current epoch, would return InvalidEpoch() error while upvote/downvote.

Expected behavior
Since we need the reputation proof before user does any action, so need to do ust before upvote/downvote.

[cc03668]

@Xiawpohr 想確認我們上次討論完，是不是有確認到如果 vote 是該 epoch 第一個動作的話，我們都會做 state transition 呢？