Implement Routes to Filter Polls by Participation and Creation

[tran2106]

Add GET /api/polls/participated route

Returns a list of polls where the current user has submitted a vote
Label these polls as “participated” in the response
Allow frontend to filter and display participated polls separately

Add GET /api/polls/created route:

Returns a list of polls created by the current (logged-in) user
Label these polls as “created” in the response
Allow frontend to filter and display created polls separately