feat(landing): warm up the contact CTAs (#412)

Give the contact calls-to-action a friendlier, more human voice. The nav
"Contact" link and the FAQ "Contact Us" button become "Talk to a human",
and the Enterprise pricing "Contact Sales" becomes "Let's talk". All links
still point to /contact; only the labels change.

Claude-Session: https://claude.ai/code/session_01MbQGV1k1mneFidgGyDnmDQ

apps/landing/src/components/Pricing.astro

@@ -79,7 +79,7 @@ const checkIcon =
           href="/contact"
           class="btn-primary mt-6 block rounded-xl px-6 py-3 text-center text-sm font-semibold"
         >
-          Contact Sales
+          Let's talk
         </a>
 
         <ul class="mt-8 space-y-3">