fix(tasks): isolate worker execution scopes

Persist a required Server-owned execution scope and enforce it for listing, claiming, lease recovery and SCADA verification. Backfill existing tasks explicitly through migration 034 so local development workers no longer claim production tasks from the shared database.

app/services/operational_recovery.py

@@ -131,9 +131,11 @@ async def reconcile_recoveries(service: OperationalTaskService, timescale: Async
     from app.infra.db.timescaledb.repositories.scada import ScadaRepository
 
     async with service.repo.transaction():
-        candidates = await service.repo.recovery_candidates(limit, created_from)
+        candidates = await service.repo.recovery_candidates(limit, created_from, service.execution_scope)
     resumed = 0
     for task in candidates:
+        if task.get("execution_scope") != service.execution_scope:
+            continue
         context = task["handling_context"]
         returned_at = datetime.fromisoformat(context["returned_at"])
         incident_at = datetime.fromisoformat(task["trigger"]["occurred_at"])