fix(tests): vault fixture removes its temp dir

tests/test_policy.py

@@ -1,4 +1,6 @@
+import shutil
 import tempfile
+from collections.abc import Iterator
 from pathlib import Path
 
 import pytest
@@ -15,13 +17,16 @@ from beaver_agent.policy import (
 
 
 @pytest.fixture
-def vault() -> Path:
+def vault() -> Iterator[Path]:
     root = Path(tempfile.mkdtemp(prefix="beaver-vault-"))
+    try:
         for d in ("мета/бобер", "💬 чаты", "📅 дни", "👤 люди"):
             (root / d).mkdir(parents=True)
         (root / "💬 чаты/старый.md").write_text("x")
         (root / "📅 дни/2026-08-29.md").write_text("x")
-    return root
+        yield root
+    finally:
+        shutil.rmtree(root, ignore_errors=True)
 
 
 @pytest.fixture