feat: replace all booking CTAs with BookedIn scheduling link

Replace /contact/ booking links sitewide with the BookedIn external
scheduling URL (https://bookedin.com/book/lahr-carpet-cleaning-and-upholstery).
All "Book Now" and "Get a Free Estimate" buttons across 38 HTML pages now
open the BookedIn scheduler in a new tab. Added a "Book Online" CTA button
to the shared nav bar and a booking link in the footer (components.js).
The contact page retains its form as a secondary option, with a prominent
"Book Online Instantly" banner added above it.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

about/index.html

@@ -20,7 +20,7 @@
                 <span class="hero-eyebrow">Waterloo, NY &mdash; Finger Lakes Region</span>
                 <h1>About <span class="text-accent">Lahr</span> Carpet Cleaning</h1>
                 <p>Local, reliable carpet care that treats your home with respect.</p>
-                <a href="/contact/" class="btn btn-primary btn-large">Book Now</a>
+                <a href="https://bookedin.com/book/lahr-carpet-cleaning-and-upholstery" target="_blank" rel="noopener noreferrer" class="btn btn-primary btn-large">Book Now</a>
             </div>
         </div>
     </section>
@@ -108,7 +108,7 @@
         <div class="cta-content">
             <h2 class="heading-4"><strong>Ready to See the </strong><span class="text-accent"><strong>Difference</strong></span><strong>?</strong></h2>
             <p class="paragraph-4">Call us or fill out our contact form. Free estimates included with every booking.</p>
-            <a href="/contact/" class="btn btn-primary">Book Now</a>
+            <a href="https://bookedin.com/book/lahr-carpet-cleaning-and-upholstery" target="_blank" rel="noopener noreferrer" class="btn btn-primary">Book Now</a>
         </div>
     </section>