fix: recover failed Gaussian project builds

src/k1link/web/simulation_projects_api.py

@@ -176,13 +176,15 @@ def build_simulation_projects_router(
         background_tasks: BackgroundTasks,
     ) -> dict[str, Any]:
         try:
-            project = store.begin_build(project_id)
+            project = service.begin_build(project_id)
             background_tasks.add_task(service.process, project_id)
             return project
         except SimulationProjectNotFoundError as exc:
             raise HTTPException(status_code=404, detail="Проект симуляции не найден.") from exc
         except SimulationProjectConflictError as exc:
             raise HTTPException(status_code=409, detail=str(exc)) from exc
+        except GaussianPipelineGatewayError as exc:
+            raise HTTPException(status_code=503, detail=str(exc)) from exc
 
     @router.delete("/projects/{project_id}", status_code=204)
     def delete_project(project_id: str) -> Response: