fix: pipeline selected round ring cutoff by overflow scroll

Add vertical padding to the scrollable pipeline container so
the ring-2 highlight on selected rounds isn't clipped.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/observer/observer-dashboard-content.tsx

@@ -197,7 +197,7 @@ export function ObserverDashboardContent({ userName }: { userName?: string }) {
                 ))}
               </div>
             ) : roundOverview && roundOverview.rounds.length > 0 ? (
-              <div className="flex items-stretch gap-0 overflow-x-auto pb-2">
+              <div className="flex items-stretch gap-0 overflow-x-auto py-1 -my-1">
                 {roundOverview.rounds.map((round, idx) => {
                   const isSelected = selectedRoundId === round.roundId
                   const isActive = round.roundStatus === 'ROUND_ACTIVE'