This pull request introduces the following changes:
1. **Exclude translated pages from search**: I explored ways to make the
search plugin work with the i18n plugin, but it would require extensive
custom JavaScript hacks. So for now, I’m holding off on this work.
2. **Switch from GPT-4.1 to o3 for even better translation quality**:
While 4.1 performs well, o3 shows even greater quality for this task,
and there’s no reason to avoid using it.
