fix(tests): repair three pre-existing gateway test failures

- test_background_autocompletes: pytest.importorskip("prompt_toolkit")
  so the test skips gracefully where the CLI dep is absent

- test_run_agent_progress_stays_in_originating_topic: update stale emoji
  💻 → ⚙️ to match get_tool_emoji("terminal", default="⚙️") in run.py

- test_internal_event_bypass{_authorization,_pairing}: mock
  _handle_message_with_agent to raise immediately; avoids the 300s
  run_in_executor hang that caused the tests to time out

tests/gateway/test_background_command.py

@@ -308,6 +308,7 @@ class TestBackgroundInCLICommands:
 
     def test_background_autocompletes(self):
         """The /background command appears in autocomplete results."""
+        pytest.importorskip("prompt_toolkit")
         from hermes_cli.commands import SlashCommandCompleter
         from prompt_toolkit.document import Document