Refine Swiss + Editorial themes; add optional date field

Swiss: drop all-caps on titles, soften heavy ink borders to muted rules
or remove them where background contrast carries the form, balance hero
name weights (smaller lighter first name vs heavier italic last name),
fix unreadable white description text on portfolio hover.

Editorial: enlarge the section "No" mark and set it in italic Fraunces so
it reads as typography instead of a tick, swap the first name into DM
Serif Display for a different J, sharpen the section number caption.

Client tile: contain custom logos at 86% so wide marks like
"The Cooperative Way" stop getting cropped to "operative".

New: optional `date` field on every item type (link/card/portfolio/
youtube/client). Accepts YYYY, YYYY-MM, or YYYY-MM-DD. Rendered
human-friendly with the raw ISO preserved in <time datetime>.
Documented in README and demonstrated in links.example.json.

index.html

@@ -19,7 +19,7 @@
 
   <!-- Editorial: Fraunces (variable serif) + Geist (refined sans) + Geist Mono
        Swiss: Archivo (variable grotesque, near-Akzidenz/Univers) -->
-  <link href="https://fonts.googleapis.com/css2?family=Archivo:wght@400;500;600;700;900&family=Fraunces:opsz,wght,SOFT,WONK@9..144,300..600,30..100,0..1&family=Geist:wght@300;400;500;600&family=Geist+Mono:wght@400;500&display=swap" rel="stylesheet">
+  <link href="https://fonts.googleapis.com/css2?family=Archivo:wght@400;500;600;700;900&family=DM+Serif+Display:ital@0;1&family=Fraunces:opsz,wght,SOFT,WONK@9..144,300..600,30..100,0..1&family=Geist:wght@300;400;500;600&family=Geist+Mono:wght@400;500&display=swap" rel="stylesheet">
 
   <script>
     // Apply saved theme + template before paint to avoid flash