Remove 1000-result limit, add Redis caching and virtual scrolling

- Remove hard-coded limit=1000 default from listing_geojson and streaming
  endpoints, allowing all matching results to be returned
- Add Redis caching service (db=2, 30min TTL) that caches query results
  as Redis Lists for fast re-queries with reduced DB load
- Integrate cache into streaming endpoint: serve from cache on hit,
  populate cache on miss during DB streaming
- Invalidate cache after scrape completes (both success and no-new-listings)
- Replace ScrollArea with react-virtuoso in ListView for virtual scrolling,
  keeping only ~20-30 DOM nodes regardless of list size
- Handle metadata streaming message to show "0 / N" progress from start
- Throttle frontend state updates with requestAnimationFrame to prevent
  UI jank from rapid re-renders during cached response streaming

crawler/tasks/listing_tasks.py

@@ -16,6 +16,7 @@ from repositories.listing_repository import ListingRepository
 from database import engine
 from services.query_splitter import QuerySplitter, SubQuery
 from utils.redis_lock import redis_lock
+from services.listing_cache import invalidate_cache
 
 logger = logging.getLogger("uvicorn.error")
 
@@ -88,6 +89,7 @@ async def dump_listings_full(
     if len(ids_to_process) == 0:
         elapsed = time.time() - start_time
         celery_logger.info(f"No new listings found. Completed in {elapsed:.1f}s")
+        invalidate_cache()
         task.update_state(
             state="No new listings found",
             meta={"progress": 1, "processed": 0, "total": 0, "message": "All listings are up to date"},
@@ -111,6 +113,8 @@ async def dump_listings_full(
     celery_logger.info(f"COMPLETED: Processed {len(result)} listings in {elapsed:.1f}s")
     celery_logger.info("=" * 60)
 
+    invalidate_cache()
+
     return result