New reading.html renders the data file into a #reading-list container and
marks itself as the current page. Home and contact pages gain a Reading nav
link. CSS adds responsive category/list styles (two columns on wide
screens) so long lists stay scannable.
Renders the data file as category-grouped HTML. Pure string builder with
guarded browser wiring so it is unit-testable in Node; escapes all text,
skips invalid entries, and handles duplicate category slugs.
Single source of truth for the reading list page. Entries carry a title,
url, category, and an optional one-line note; adding a link means editing
this file only.
`node --test <dir>` treats a directory argument as a module path on some
Node builds (reproduced on v22.23.2), so `npm test` failed before running
any tests. `node --test` with no args discovers the same tests/ files
portably.
bot-implementer