fix(gro-78): replace demo.groombook.io with groombook.farh.net

demo.groombook.io does not exist. Replace both CTA button links
with the actual production instance at groombook.farh.net.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

index.html

@@ -88,7 +88,7 @@
       <p class="tagline">Built for groomers, not corporations.</p>
       <p>Open source, self-hostable scheduling and client management platform built specifically for independent pet groomers. Give your business the tools of enterprise software without the enterprise price tag or vendor lock-in.</p>
       <div class="cta-buttons">
-        <a href="https://demo.groombook.io" class="btn-demo">Try the Demo →</a>
+        <a href="https://groombook.farh.net" class="btn-demo">Try the Demo →</a>
         <a href="https://github.com/groombook/groombook" class="btn-primary">View on GitHub</a>
         <a href="getting-started/" class="btn-secondary">Get Started</a>
       </div>
@@ -144,7 +144,7 @@
     <div class="container">
       <h2>See It In Action</h2>
       <p>Try the live demo environment. Log in with demo credentials to explore the full groomer and customer experience.</p>
-      <a href="https://demo.groombook.io" class="btn-demo" style="display: inline-block;">Launch Demo →</a>
+      <a href="https://groombook.farh.net" class="btn-demo" style="display: inline-block;">Launch Demo →</a>
       <p style="margin-top: 25px; color: #999; font-size: 0.95rem;">Or run it locally: <code style="background: #f0f0f0; padding: 4px 8px; border-radius: 4px;">docker compose up</code></p>
     </div>
   </section>