feat(provisioner): add optional PVC support for sandbox volumes (#2020)

* feat(provisioner): add optional PVC support for sandbox volumes (#1978)

  Add SKILLS_PVC_NAME and USERDATA_PVC_NAME env vars to allow sandbox
  Pods to use PersistentVolumeClaims instead of hostPath volumes. This
  prevents data loss in production when pods are rescheduled across nodes.

  When USERDATA_PVC_NAME is set, a subPath of threads/{thread_id}/user-data
  is used so a single PVC can serve multiple threads. Falls back to hostPath
  when the new env vars are not set, preserving backward compatibility.

* add unit test for provisioner pvc volumes

* refactor: extract shared provisioner_module fixture to conftest.py

Agent-Logs-Url: https://github.com/bytedance/deer-flow/sessions/e7ccf708-c6ba-40e4-844a-b526bdb249dd

Co-authored-by: WillemJiang <219644+WillemJiang@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: JeffJiang <for-eleven@hotmail.com>

backend/tests/conftest.py

@@ -4,10 +4,13 @@ Sets up sys.path and pre-mocks modules that would cause circular import
 issues when unit-testing lightweight config/registry code in isolation.
 """
 
+import importlib.util
 import sys
 from pathlib import Path
 from unittest.mock import MagicMock
 
+import pytest
+
 # Make 'app' and 'deerflow' importable from any working directory
 sys.path.insert(0, str(Path(__file__).parent.parent))
 sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "scripts"))
@@ -32,3 +35,21 @@ _executor_mock.MAX_CONCURRENT_SUBAGENTS = 3
 _executor_mock.get_background_task_result = MagicMock()
 
 sys.modules["deerflow.subagents.executor"] = _executor_mock
+
+
+@pytest.fixture()
+def provisioner_module():
+    """Load docker/provisioner/app.py as an importable test module.
+
+    Shared by test_provisioner_kubeconfig and test_provisioner_pvc_volumes so
+    that any change to the provisioner entry-point path or module name only
+    needs to be updated in one place.
+    """
+    repo_root = Path(__file__).resolve().parents[2]
+    module_path = repo_root / "docker" / "provisioner" / "app.py"
+    spec = importlib.util.spec_from_file_location("provisioner_app_test", module_path)
+    assert spec is not None
+    assert spec.loader is not None
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module