test: derive XDG temp path via tempfile.gettempdir() (Ruff S108)

CodeRabbit flagged the hardcoded `/tmp/some-xdg-root` literal in
test_uses_xdg_state_home_when_set: it's Linux-specific and trips
Ruff's S108 (hardcoded-tmp-directory) lint. Derive the path from
tempfile.gettempdir() and join with os.path.join so the test runs
on Windows / macOS too and stays lint-clean.

Author: timon0305

tests/test_cli_export_e2e.py

@@ -134,10 +134,11 @@ def tearDown(self):
             os.environ["XDG_STATE_HOME"] = self._prior
 
     def test_uses_xdg_state_home_when_set(self):
-        os.environ["XDG_STATE_HOME"] = "/tmp/some-xdg-root"
+        xdg_root = os.path.join(tempfile.gettempdir(), "some-xdg-root")
+        os.environ["XDG_STATE_HOME"] = xdg_root
         self.assertEqual(
             export_script.get_global_state_dir(),
-            "/tmp/some-xdg-root/cursor-chat-browser",
+            os.path.join(xdg_root, "cursor-chat-browser"),
         )
 
     def test_falls_back_to_home_when_xdg_unset(self):