Add real-time WebSocket task progress with multi-job drawer

Replace 5s HTTP polling with WebSocket-based real-time updates for task
progress. Celery workers publish progress to Redis pub/sub channels;
a FastAPI WebSocket endpoint subscribes and forwards to the browser.
Polling is kept as a 30s fallback when WebSocket is unavailable.

The task progress drawer now supports multiple concurrent jobs with a
tab bar for switching between scrape and POI distance tasks.

Backend:
- Add services/task_progress_publisher.py (Redis pub/sub bridge)
- Add api/ws_routes.py (WebSocket endpoint with JWT auth)
- Publish progress from listing_tasks and poi_tasks
- Publish REVOKED via pub/sub on cancel/clear to fix stuck UI

Frontend:
- Add useTaskWebSocket hook with reconnection and keepalive
- Add TaskState and WS message types
- TaskIndicator: WS-driven updates with polling fallback
- TaskProgressDrawer: multi-job tabs, POI phase timeline
- Guard against WS overwriting local cancel state

tasks/poi_tasks.py

@@ -10,6 +10,7 @@ from models.listing import ListingType
 from repositories.listing_repository import ListingRepository
 from repositories.poi_repository import POIRepository
 from services.poi_distance_calculator import calculate_poi_distances
+from services.task_progress_publisher import publish_task_progress
 
 logger = logging.getLogger(__name__)
 
@@ -55,6 +56,11 @@ def calculate_poi_distances_task(
         "progress": 0,
         "message": "Starting distance calculation...",
     })
+    publish_task_progress(self.request.id, "PROGRESS", {
+        "phase": "starting",
+        "progress": 0,
+        "message": "Starting distance calculation...",
+    })
 
     listing_repo = ListingRepository(engine)
     poi_repo = POIRepository(engine)
@@ -62,19 +68,23 @@ def calculate_poi_distances_task(
     poi = poi_repo.get_poi_by_id(poi_id)
     if poi is None:
         celery_logger.error(f"POI {poi_id} not found")
-        return {"error": f"POI {poi_id} not found", "distances_computed": 0}
+        error_result = {"error": f"POI {poi_id} not found", "distances_computed": 0}
+        publish_task_progress(self.request.id, "FAILURE", error_result)
+        return error_result
 
     lt = ListingType(listing_type)
 
     def on_progress(completed: int, total: int, message: str) -> None:
         progress = round(completed / total, 2) if total > 0 else 0
-        self.update_state(state="PROGRESS", meta={
+        meta = {
             "phase": "computing",
             "progress": progress,
             "processed": completed,
             "total": total,
             "message": message,
-        })
+        }
+        self.update_state(state="PROGRESS", meta=meta)
+        publish_task_progress(self.request.id, "PROGRESS", meta)
 
     try:
         total = asyncio.run(
@@ -96,9 +106,12 @@ def calculate_poi_distances_task(
 
     celery_logger.info(f"POI distance calculation complete: {total} distances computed")
 
-    return {
+    result = {
         "phase": "completed",
         "progress": 1,
         "distances_computed": total,
         "message": f"Computed {total} distances for POI '{poi.name}'",
     }
+    publish_task_progress(self.request.id, "SUCCESS", result)
+
+    return result