Address claude-review round 5 on PR #868: add test_all_blank_pages_returns_empty_list documenting that PageAwareChunker returns [] when every page is blank — and asserting parity with DocumentChunker, which already returns [] for whitespace-only non-empty content. The empty-chunk-list case is therefore pre-existing pipeline behavior, not new to this PR. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>