Fix empty pages in document search results

## Change

Offline fixture candidate removing an empty document page.

## Validation

- Acceptance tests: 6 run, 0 failures, 0 errors.
- Independent Codex review: approve. Offline fixture review; no model or provider was called.
- Boundary comparison: passed.
- Human decision: approved.
- Workflow: `wf_554f7250-3112-45cb-900a-77a140197772`.
- Candidate SHA-256: `055be74f94305213e9dd7e1a19bd9f05cb8615b46b45ed29940cf80201672a1b`.
- Bundled base SHA-256: `bff4585b53828fc8969df92649abb46a1fcc94f3465f30ba6cee02d5dc5e6841`.

## Release note draft

No more empty document pages

Document lists now end on the last populated page, including exactly 100 documents. Offline fixture note; no provider called.

No merge or deployment is performed.