content: Kontakt/Impressum-Seite + Footer-Link

- content/impressum.md: Kontakt (E-Mail/Dialog) + Impressum (Karim Varano,
  Fluhmühlerain 1, 6015 Luzern, Privatperson)
- footer: „Kontakt"-Mailto → /impressum/ („Kontakt / Impressum")

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

layouts/_partials/footer.html

@@ -10,7 +10,7 @@
   </div>
   <nav class="footer-links" aria-label="Footer">
     <a href="/colophon/">Colophon</a>
-    <a href="mailto:karim@gabrielevarano.ch">Kontakt</a>
+    <a href="/impressum/">Kontakt / Impressum</a>
     <a href="/index.xml">RSS</a>
     <a href="/spenden/">Spenden</a>
   </nav>