Feature/fsg gamma team ui fix (#3)

## Summary

What changed and why?

## Change Type

- [ ] Cowork feature
- [ ] Bug fix
- [x] Core AI contribution
- [ ] Test / hardening
- [ ] Performance
- [ ] Documentation

## Related Work

Cowork Task:

Core Repo: http://34.143.229.138/gitea-admin/fsg-ai-core-assets

Core AI Issue:

Core Task:

Related PR:

## Scope

What is intentionally included?

What is intentionally NOT included?

## Validation

- [ ] Unit tests
- [ ] Integration tests
- [ ] Manual verification
- [ ] Regression check

Commands / evidence:

## Security Impact

Permission / credential / network / customer data impact:

## Compatibility

- [ ] No breaking change
- [ ] Breaking change documented

## Reviewer Notes

Anything Cowork reviewers should pay attention to.

---------

Co-authored-by: Hiep Ha Van <hiephv3@fpt.com>
Co-authored-by: Nam Pham Dinh Thanh <nampdt@fpt.com>
Co-authored-by: Lam Hoang Van <lamhv7@fpt.com>
Co-authored-by: NamPDT <minhanhpkpro@gmail.com>
Reviewed-on: #3

ui/sidebar.py

@@ -164,6 +164,9 @@ class HistorySidebar(QWidget):
         self._refresh_btn.setToolTip(tr("sidebar.refresh_tooltip"))
         self.refresh()   # re-render group headers / running suffix in the new language
 
+    def is_collapsed(self) -> bool:
+        return self._strip.isVisible()
+
     def set_collapsed(self, collapsed: bool) -> None:
         """Collapse to a thin line (kept visible) or restore the full panel."""
         self._content.setVisible(not collapsed)