* Add UI for advanced search
To help users with the seach operators.
Obviously not as powerful as a manually-written search query.
Lack in particular negation and logical *and* for now, but I might try to do something about it.
<img width="939" height="1438" alt="image" src="https://github.com/user-attachments/assets/0bcad39b-eff3-4f44-876b-a2552af2af00" />
* Consistency: allow multiple user queries like S:1,2
* Fix user query and add tests
