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

fix: block document access for users not in annotator_config

feat: multi-corpus support

feat: per-annotator document assignments with configurable overlap

fix: remove PDF HEAD check that was filtering out valid docs (WB returns 301 for HEAD)

feat: prepare_data.py script + use has_revalidation filter in documents API

fix: validate PDF URLs before listing documents, skip broken/unreachable PDFs

feat: add loading spinner and error fallback to PDF viewer

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

update: reverted local changes

feat: per-annotator document assignment

feat: human validation, recursive highlighting, data mentions rename

feat: implement HF Datasets remote fetching and save

feat: implement dual local/HF storage with page-level UI tracking