refactor(tests): reorganize tests into unittest/ and e2e/ directories

- Move all unit tests from tests/ to tests/unittest/
- Add tests/e2e/ directory for end-to-end tests
- Update conftest.py for new test structure
- Add new tests for auth dependencies, policies, route injection
- Add new tests for run callbacks, create store, execution artifacts
- Remove obsolete tests for deleted persistence layer

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/tests/unittest/test_skills_archive_root.py

@@ -0,0 +1,41 @@
+from pathlib import Path
+
+import pytest
+
+from deerflow.skills.installer import resolve_skill_dir_from_archive
+
+
+def _write_skill(skill_dir: Path) -> None:
+    skill_dir.mkdir(parents=True, exist_ok=True)
+    (skill_dir / "SKILL.md").write_text(
+        """---
+name: demo-skill
+description: Demo skill
+---
+
+# Demo Skill
+""",
+        encoding="utf-8",
+    )
+
+
+def test_resolve_skill_dir_ignores_macosx_wrapper(tmp_path: Path) -> None:
+    _write_skill(tmp_path / "demo-skill")
+    (tmp_path / "__MACOSX").mkdir()
+
+    assert resolve_skill_dir_from_archive(tmp_path) == tmp_path / "demo-skill"
+
+
+def test_resolve_skill_dir_ignores_hidden_top_level_entries(tmp_path: Path) -> None:
+    _write_skill(tmp_path / "demo-skill")
+    (tmp_path / ".DS_Store").write_text("metadata", encoding="utf-8")
+
+    assert resolve_skill_dir_from_archive(tmp_path) == tmp_path / "demo-skill"
+
+
+def test_resolve_skill_dir_rejects_archive_with_only_metadata(tmp_path: Path) -> None:
+    (tmp_path / "__MACOSX").mkdir()
+    (tmp_path / ".DS_Store").write_text("metadata", encoding="utf-8")
+
+    with pytest.raises(ValueError, match="empty"):
+        resolve_skill_dir_from_archive(tmp_path)