Adds newsletter.html with an email signup form that POSTs to a configured
serverless endpoint. The endpoint and API token live in
js/newsletter-config.js (token defaults to an empty deploy-time placeholder,
never hardcoded in page logic). Missing/invalid tokens and network failures
surface a fixed user-safe error; successful signups show a confirmation.
Links the page from the site navigation on all pages.
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.
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