fix(tests): isolate HERMES_HOME in tests and adjust log directory for debug session

Added a fixture to redirect HERMES_HOME to a temporary directory during tests, preventing writes to the user's home directory. Updated the test for DebugSession to create a dedicated log directory for saving logs, ensuring test isolation and accuracy in assertions.

tests/tools/test_debug_helpers.py

@@ -26,9 +26,11 @@ class TestDebugSessionDisabled:
 
     def test_save_noop(self, tmp_path):
         ds = DebugSession("test_tool", env_var="FAKE_DEBUG_VAR_XYZ")
-        ds.log_dir = tmp_path
+        log_dir = tmp_path / "debug_logs"
+        log_dir.mkdir()
+        ds.log_dir = log_dir
         ds.save()
-        assert list(tmp_path.iterdir()) == []
+        assert list(log_dir.iterdir()) == []
 
     def test_get_session_info_disabled(self):
         ds = DebugSession("test_tool", env_var="FAKE_DEBUG_VAR_XYZ")