Add tappable cards, detail bottom sheet, swipe gestures, and favorites view

- Decision types, services (decisionService, listingDetailService), and index exports
- useDecisions hook with optimistic updates and Map-based state
- useListingDetail hook with session-level caching
- PhotoCarousel component using embla-carousel-react
- ListingDetail component with full property info, like/dislike buttons
- ListingDetailSheet using vaul Drawer (slide-up bottom sheet)
- SwipeablePropertyCard with @use-gesture/react and @react-spring/web
- SwipeReviewMode for mobile full-screen swipe review
- FavoritesView with virtualized liked listings and remove button
- App.tsx integration: decision state, client-side disliked filtering, detail sheet, swipe handlers
- ListView conditionally renders SwipeablePropertyCard when handlers provided
- StatsBar adds 'saved' view mode with heart icon
- Header adds liked count indicator
- New deps: vaul, embla-carousel-react, @use-gesture/react, @react-spring/web

frontend/src/components/FavoritesView.tsx

@@ -0,0 +1,80 @@
+import { useMemo } from 'react';
+import { Virtuoso } from 'react-virtuoso';
+import { Heart, X } from 'lucide-react';
+import { PropertyCard } from './PropertyCard';
+import type { GeoJSONFeatureCollection, DecisionType } from '@/types';
+
+interface FavoritesViewProps {
+  listingData: GeoJSONFeatureCollection;
+  getDecision: (listingId: number, listingType?: string) => DecisionType | undefined;
+  onSelectListing?: (id: number) => void;
+  onRemoveFavorite?: (id: number, listingType: 'RENT' | 'BUY') => void;
+}
+
+function getListingId(url: string): number {
+  const parts = url.split('/');
+  return parseInt(parts[parts.length - 1], 10);
+}
+
+export function FavoritesView({ listingData, getDecision, onSelectListing, onRemoveFavorite }: FavoritesViewProps) {
+  const favorites = useMemo(() => {
+    return listingData.features.filter((f) => {
+      const id = f.properties.id ?? getListingId(f.properties.url);
+      const type = f.properties.listing_type === 'BUY' ? 'BUY' : 'RENT';
+      return getDecision(id, type) === 'liked';
+    });
+  }, [listingData.features, getDecision]);
+
+  if (favorites.length === 0) {
+    return (
+      <div className="h-full flex items-center justify-center">
+        <div className="text-center p-8">
+          <Heart className="h-12 w-12 mx-auto mb-4 text-muted-foreground" />
+          <h2 className="text-lg font-semibold mb-2">No favorites yet</h2>
+          <p className="text-muted-foreground text-sm">
+            Swipe right or tap the heart button on listings you like
+          </p>
+        </div>
+      </div>
+    );
+  }
+
+  return (
+    <div className="h-full flex flex-col bg-background">
+      <div className="px-3 py-2 text-sm text-muted-foreground border-b flex items-center gap-2">
+        <Heart className="h-4 w-4 text-green-600 fill-current" />
+        {favorites.length} saved {favorites.length === 1 ? 'listing' : 'listings'}
+      </div>
+      <Virtuoso
+        className="flex-1"
+        data={favorites}
+        overscan={200}
+        itemContent={(_index, feature) => {
+          const id = feature.properties.id ?? getListingId(feature.properties.url);
+          const type = feature.properties.listing_type === 'BUY' ? 'BUY' : 'RENT';
+          return (
+            <div className="px-3 pb-2 first:pt-3 relative">
+              <PropertyCard
+                property={feature.properties}
+                variant="compact"
+                onClick={() => onSelectListing?.(id)}
+              />
+              {onRemoveFavorite && (
+                <button
+                  className="absolute top-4 right-4 p-1 rounded-full bg-red-100 text-red-600 hover:bg-red-200 transition-colors"
+                  onClick={(e) => {
+                    e.stopPropagation();
+                    onRemoveFavorite(id, type);
+                  }}
+                  title="Remove from favorites"
+                >
+                  <X className="h-3.5 w-3.5" />
+                </button>
+              )}
+            </div>
+          );
+        }}
+      />
+    </div>
+  );
+}