a11y(polls): drop redundant aria-label on max-selections input

Review noted the number input had both an htmlFor-associated visible label
("Voters can pick up to") and an aria-label, so the aria-label won and the
visible label was not announced. Remove the aria-label so the accessible name
matches the visible label.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/features/room/PollCreator.tsx

@@ -247,7 +247,6 @@ export function PollCreator({ roomId, onClose }: PollCreatorProps) {
                         )
                       }
                       style={{ width: '4rem' }}
-                      aria-label="Maximum selections per voter"
                     />
                     <Text size="T200" priority="300">
                       of {options.length} options