feat(04-01): add Wave 0 xfail stubs for DOC-02, ADMIN-06, SEC-08, SEC-09

- test_documents.py: append 4 stubs (content_stream 200, 206, admin_403, no_presigned_url)
- test_audit.py: create new file with 4 stubs (viewer, no_doc_content, user_403, export_csv)
- test_security.py: create new file with 2 stubs (credentials_enc_not_in_response, delete_user_cleans_files)
- All stubs: xfail(strict=False), body is pytest.xfail("not implemented yet")

backend/tests/test_audit.py

@@ -0,0 +1,43 @@
+"""
+Audit log API tests — Wave 0 xfail stubs for Phase 4.
+
+All tests in this file are xfail stubs. They will be implemented in Plan 04-07.
+The stubs ensure pytest collects them and keeps CI green before implementation
+code exists.
+
+Requirement: ADMIN-06 — admin audit log viewer, no doc content, export CSV.
+"""
+from __future__ import annotations
+
+import os
+
+import pytest
+
+
+# ---------------------------------------------------------------------------
+# ADMIN-06: Audit log viewer
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.xfail(strict=False)
+async def test_audit_log_viewer(async_client, admin_user):
+    """GET /api/admin/audit-log returns paginated entries."""
+    pytest.xfail("not implemented yet")
+
+
+@pytest.mark.xfail(strict=False)
+async def test_audit_log_no_doc_content(async_client, admin_user):
+    """Audit log entries contain no 'filename' or 'extracted_text' keys in metadata."""
+    pytest.xfail("not implemented yet")
+
+
+@pytest.mark.xfail(strict=False)
+async def test_audit_log_regular_user_403(async_client, auth_user):
+    """GET /api/admin/audit-log with regular user token returns 403."""
+    pytest.xfail("not implemented yet")
+
+
+@pytest.mark.xfail(strict=False)
+async def test_audit_log_export_csv(async_client, admin_user):
+    """GET /api/admin/audit-log/export?format=csv returns CSV content-type."""
+    pytest.xfail("not implemented yet")