Refactor: replace all BEM CSS with Tailwind utility classes

Remove all BEM component classes (hero__*, card__*, issue-card__*, foot__*,
masthead__*, searchpop__*, lb__*) from CSS and templates. Replace with
Tailwind v4 utility classes inline in HTML. Create card.html partial to
avoid repeating verbose utility strings across grid templates. Rename
lightbox CSS to flat lb-* and search popup to sp-*.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

layouts/partials/logo.html

@@ -1,5 +1,5 @@
-<span class="logo">
-  <svg class="logo__mark" viewBox="0 0 64 64" aria-hidden="true">
+<span class="grid justify-items-center gap-1 text-center">
+  <svg class="block w-[30px] h-[30px] max-[620px]:w-[22px] max-[620px]:h-[22px]" viewBox="0 0 64 64" aria-hidden="true">
     <defs>
       <radialGradient id="mhBloom" cx="50%" cy="46%" r="58%">
         <stop offset="0" stop-color="#b34a30"/>
@@ -33,6 +33,6 @@
     <circle cx="32" cy="32" r="3.2" fill="#3a120c"/>
     <circle cx="32" cy="31.4" r="1.2" fill="#c0573c" opacity=".7"/>
   </svg>
-  <span class="logo__word">Roux</span>
-  <span class="logo__tag">Le Journal · Paris</span>
+  <span class="font-display font-normal text-[30px] leading-none tracking-[.045em] text-ink max-[620px]:text-[22px]">Roux</span>
+  <span class="font-sans font-medium text-[8.5px] leading-none tracking-[.32em] uppercase text-ink-soft max-[620px]:text-[7.5px] max-[620px]:tracking-[.28em]">Le Journal · Paris</span>
 </span>