Adds /corpus.php — a data transparency page showing what powers the
legal tools: 9 coverage categories with live doc counts, a full
sources table pulled from the corpus DB, the AI stack (LLMs, Whisper,
Qdrant, Azure AI Search, embeddings, chunking), and a pipeline flow
diagram. Stats are live via a new /api/corpus-stats.php endpoint
(queries dobetter_rag + bnl_admin). The reasoning sidebar is repurposed
as a Corpus health panel on this page.
Also ships the in-progress timeline background events toggle:
API and UI wired together via include_background param.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
