fix(test): emit response event on gemini_cli timeout

- Add try/except in ai_client.py to emit response_received event
  before re-raising exceptions from gemini_cli adapter
- Adjust mock_gemini_cli.py to sleep 65s (triggers 60s adapter timeout)
- This fixes test_mock_timeout and other live GUI tests that were
  hanging because no event was emitted on timeout

tests/mock_gemini_cli.py

@@ -16,7 +16,7 @@ def main() -> None:
   sys.exit(1)
  elif mock_mode == "timeout":
   import time
-  time.sleep(120)
+  time.sleep(65)
   sys.exit(1)
 
  # Read prompt from stdin