Add booking checkout and webhook flow

src/app/page.tsx

@@ -70,9 +70,9 @@ export default function HomePage() {
                 <input aria-label={field.label} defaultValue={field.value} />
               </label>
             ))}
-            <button className="btn btn-dark" type="button">
+            <Link className="btn btn-dark" href="/bookings/new">
               Check availability
-            </button>
+            </Link>
           </form>
 
           <div className="quote-panel" aria-label="Booking quote preview">