feat: add in-app help guide with ❓ button in top bar

feat: show all pages with jump-to-mention navigation

fix: extend highlighting to headings, strong, em, blockquote

ui: 5 polish fixes

feat: multi-corpus support

feat: add refresh button to leaderboard + cache-bust API calls

feat: add annotation leaderboard with medals and stats

feat: per-annotator validation support for multi-user overlap

refactor: make progress bar contextual - shows current PDF/page/mentions position

feat: add progress tracking with docs/pages/mentions verification stats

fix: proxy PDFs through /api/pdf-proxy to bypass CORS

feat: add loading spinner and error fallback to PDF viewer

feat: on-demand document loading, no limit, PDF loading indicator

fix: use _rawIndex for delete/validate to avoid index mismatch after filtering

fix: rename 'Your Name' to 'Annotator', make read-only, auto-populated from OAuth

filter: hide consensus non-datasets (model + judge agree)

feat: human validation, recursive highlighting, data mentions rename