feat(GRO-1791): add Book Now CTA to landing page hero and navigation

- Add "Book an Appointment" as first CTA button in hero section, linking
  to https://groombook.dev/admin/book
- Add "Book Now" to footer navigation links
- Add "Book an Appointment" quick-link to getting-started page
- Preserve all existing CTAs (Try Demo, Get Started, View on GitHub)

cc @cpfarhood

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

getting-started/index.html

@@ -109,6 +109,7 @@
   <h2>Quick Links</h2>
 
   <ul>
+    <li><a href="https://groombook.dev/admin/book">Book an Appointment →</a></li>
     <li><a href="https://github.com/groombook/groombook">GitHub Repository</a></li>
     <li><a href="https://github.com/groombook/groombook/issues">Report an Issue</a></li>
     <li><a href="https://discord.gg/groombook">Join Our Discord</a></li>

index.html

@@ -99,6 +99,7 @@
       <p class="tagline">Stop missing client calls. Book 24/7, groom all day.</p>
       <p>Built for solo groomers and small teams who want to own their schedule and their data. Clients book themselves 24/7. You groom. Automated reminders, detailed pet profiles, and mobile-first tools mean more time grooming, less time on admin.</p>
       <div class="cta-buttons">
+        <a href="https://groombook.dev/admin/book" class="btn-primary">Book an Appointment →</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>
@@ -340,6 +341,7 @@
       <p><strong>GroomBook</strong> — Open source scheduling and client management for independent pet groomers.</p>
       <p style="color: #999; font-size: 0.9rem; margin-top: 8px;">AGPL-3.0 License — You own this software, fully.</p>
       <div class="footer-links">
+        <a href="https://groombook.dev/admin/book">Book Now</a>
         <a href="https://github.com/groombook/groombook">GitHub</a>
         <a href="https://github.com/groombook/groombook/issues">Issues</a>
         <a href="https://discord.gg/groombook">Discord</a>