fix(marketing): A-2.8b — Loi 25 badge contrast (WCAG AA) + stale docstring

- Loi 25 article number badges (Art. 3.3, 3.5, 14): change from
  `grad-bg text-white text-xs font-black` to `bg-brand-navy text-white
  text-xs font-black`. White-on-grad-bg failed AA on the cyan/green
  portion of the gradient (~2:1 contrast); solid navy gives ~16:1.
- Update routes.py module docstring to past tense (A-2.8b is now done).
- Add regression assertion ensuring badges use solid navy, not grad-bg.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

templates/marketing/conformite.html

@@ -96,7 +96,7 @@
       <article class="bg-white p-6 rounded-[14px] border border-brand-border">
         <div class="flex flex-col md:flex-row md:items-start gap-4">
           <div class="flex-shrink-0">
-            <span class="inline-block grad-bg text-white text-xs font-black px-3 py-1.5 rounded-md">{{ art.num | safe }}</span>
+            <span class="inline-block bg-brand-navy text-white text-xs font-black px-3 py-1.5 rounded-md">{{ art.num | safe }}</span>
           </div>
           <div>
             <h3 class="text-lg font-bold mb-2 text-brand-navy">{{ art.title | safe }}</h3>