Adds a grep guard (with self-test) that fails the build if any {@html ...}
expression references metaDateRaw/documentDateRaw/rawDate. meta_date_raw is
untrusted verbatim spreadsheet text and must render via Svelte default
escaping (CWE-79). Addresses Nora's regression-guard request from #666 — a
single component test cannot catch a future {@html} introduced elsewhere.
Refs #666
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2bd5c82826