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_run_progress_topics.py

@@ -144,7 +144,7 @@ async def test_run_agent_progress_stays_in_originating_topic(monkeypatch, tmp_pa
     assert adapter.sent == [
         {
             "chat_id": "-1001",
-            "content": '💻 terminal: "pwd"',
+            "content": '⚙️ terminal: "pwd"',
             "reply_to": None,
             "metadata": {"thread_id": "17585"},
         }