Enrich and parallelise static term-page generation

Generate full term pages from get_term_info (cross-references, class example downloads, graphs-for), emit Goldmark-safe HTML (full <table> for query previews, anchors inside the hero block, blank-line section separation), and fetch concurrently via a bounded worker pool. Bumps page version 8->9 to force a full regeneration. Syncs the change from VFB2-draft so update_vfb_terms_to_static_site picks it up.

Author: Robbie1977