fix: recreate tunnel button always creates a new tunnel

The previous endpoint blocked recreation if the tunnel was 'healthy'
or returned an 'error_response', making the Recreate Tunnel button
ineffective in many cases.

- apps/api/src/api/tool_instances.py: removed the health-check guards
  from recreate_tunnel_endpoint. It now unconditionally stops the old
  tunnel and creates a new one, then commits the new URL to the DB.
- Frontend useInstanceActions already calls onRefresh() after success,
  so the UI updates with the new tunnel URL automatically.

Quality gates: ruff clean

apps/api/src/api/tool_instances.py

@@ -2452,21 +2452,6 @@ async def recreate_tunnel_endpoint(
             detail="instance must be running to recreate tunnel",
         )
 
-    # Validate tunnel is actually broken before recreating
-    if instance.url:
-        tunnel_health = check_tunnel_health(instance.url)
-        if tunnel_health["tunnel_status"] == "error_response":
-            raise HTTPException(
-                status_code=status.HTTP_400_BAD_REQUEST,
-                detail=f"Tunnel is working but application returned HTTP {tunnel_health.get('status_code')}. Recreating the tunnel will not fix this issue.",
-            )
-        elif tunnel_health["tunnel_status"] == "healthy":
-            return {
-                "status": "healthy",
-                "url": instance.url,
-                "message": "Tunnel is already healthy",
-            }
-
     tool_type = await session.get(ToolType, instance.tool_type_id)
     if not tool_type:
         raise HTTPException(