Add tap-to-detail on swipe cards and fix color overlay alignment

- Add onTap callback to SwipeCard using useDrag's tap detection
- Wire through SwipeReviewMode to open ListingDetailSheet on tap
- Fix color overlay misalignment: add relative to card container so
  the absolute overlay positions within the rounded card, not the
  full-width outer wrapper

frontend/src/App.tsx

@@ -625,6 +625,7 @@ function App() {
           onDecide={decide}
           onClear={clear}
           onClose={() => setShowReviewMode(false)}
+          onSelectListing={(id) => setSelectedListingId(id)}
           getDecision={getDecision}
         />
       )}