New ChunkBrowserQA component replaces inline chunk browser with:
- Document sidebar with live chunk counts per regulation (batched Qdrant count API)
- Sequential chunk navigation with arrow keys (1/N through all chunks of a document)
- Overlap display showing previous/next chunk boundaries (amber-highlighted)
- Split-view with original PDF via iframe (estimated page from chunk index)
- Adjustable chunks-per-page ratio for PDF page estimation
Extracts REGULATIONS_IN_RAG and REGULATION_INFO to shared rag-constants.ts.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>