fix: remove timeout=0 from scan error toast — was causing instant dismissal

Textual's Notification expires when raised_at + timeout - time() <= 0.
With timeout=0 the toast expired immediately on mount, making the error
notification invisible to users. Drop the timeout argument to use
Textual's default display duration (~5 s).

strix/interface/tui/app.py

@@ -1403,13 +1403,12 @@ class StrixTUIApp(App):  # type: ignore[misc]
         self._scan_thread.start()
 
     def _notify_scan_error(self, exc: Exception) -> None:
-        """Dispatch a persistent error toast from any thread."""
+        """Dispatch an error toast from any thread."""
         with contextlib.suppress(Exception):
             self.call_from_thread(
                 self.notify,
                 f"Scan failed: {type(exc).__name__}: {exc}",
                 severity="error",
-                timeout=0,
             )
 
     def _capture_sdk_event(self, agent_id: str, event: Any) -> None:

tests/interface/tui/test_app.py

@@ -22,7 +22,6 @@ def test_notify_scan_error_dispatches_toast() -> None:
         app.notify,
         "Scan failed: RuntimeError: something went wrong",
         severity="error",
-        timeout=0,
     )