v0.32.1: a stuck Rabbit connection can no longer freeze the window

Opening Connections called find_device() on the GUI thread, which lists the
gvfs-MTP mount; on a wedged mount that blocks forever in an uninterruptible
FUSE wait and the app had to be force-quit. DeviceWatcher now probes on a
daemon thread (one at a time, STUCK after 3 s, late answers still land), the
menu reads its cached answer, and a stuck mount shows "Rabbit isn't
responding…" with a Reset Connection button (kill gvfsd-mtp, remount via
gio). Tests can no longer reach the real mount (conftest patches
find_device), which also takes the suite from ~200 s to ~22 s.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/conftest.py

@@ -17,6 +17,15 @@ def _isolate_eventlog(tmp_path, monkeypatch):
                         lambda: tmp_path / "control-events.log")
 
 
+@pytest.fixture(autouse=True)
+def _no_real_device(monkeypatch):
+    """No test may look at the real gvfs mount: a wedged gvfs-MTP mount
+    blocks the listing uninterruptibly and hangs the suite (Round 71).
+    Tests that need a device patch their own finder or pass a fake root."""
+    from lintunes import device_sync
+    monkeypatch.setattr(device_sync, "find_device", lambda: None)
+
+
 @pytest.fixture(scope="session")
 def qapp():
     """A Qt application so QObject/QTimer and real widgets work in tests.