Remove all Paris branding references

Journal is online-only; removed "gathered in Paris" from footer and
imprint, "· Paris" from logo tagline and 404 colophon, and the Paris
span from the header nav. Post content (paris-bridge-crimson-dusk)
left untouched as that refers to the photograph subject.

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

layouts/404.html

@@ -59,7 +59,7 @@
     {{/* Colophon mark */}}
     <div class="mt-14 flex items-center gap-5 text-ink-soft/40">
       <div class="h-px w-12 bg-current"></div>
-      <span class="font-serif italic text-[13px] text-ink-soft/50">Roux · Paris</span>
+      <span class="font-serif italic text-[13px] text-ink-soft/50">Roux</span>
       <div class="h-px w-12 bg-current"></div>
     </div>