Safari on iOS automatically inflates text it considers small, causing code
blocks to appear much larger than intended. Adding -webkit-text-size-adjust
to a custom stylesheet as a temporary fix until the upstream theme PR is
merged.

Refs #2

* feat: disable <meta> CSP in favour of nginx response header

The CSP is now served as an HTTP response header by nginx (nix-config
modules/blog.nix) so Cloudflare can parse a per-request nonce and stamp
it onto the scripts it injects at the edge. A <meta> CSP cannot carry a
nonce and would co-enforce alongside the header, re-blocking those
scripts.

* docs: explain why CSP <meta> is disabled

Set site-wide description in zola.toml and add per-post descriptions for SEO and social sharing previews.