All reading list links point at external http(s) URLs, so each rendered
anchor now carries rel="noopener noreferrer" as a hardening best
practice. Renderer test updated for the new attribute and asserts every
rendered link carries it.
Covers: page wiring and nav reachability, data-file integrity, grouped
rendering, valid hrefs, optional notes, HTML escaping, invalid-entry
skipping, data-only extensibility, and a 500-entry fixture (counts,
grouping, and a generous render-time bound).
bot-implementer
bot-implementer