Adds static/js/member-detail.js: fetches /api/<page> once on page load,
caches the response, and renders a per-member detail modal on [i] row click.
Keyboard nav: Esc closes, ↑/↓ walk visible (filtered) rows. All modal CSS
was already in place from M6.1.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
