feat(website): Umami analytics (conversion + CTA events)

Add the Umami tracker (cookieless, no consent banner) in the document head,
limited to the production hostnames via data-domains so dev traffic doesn't
pollute the stats. Pageviews are auto-tracked per page and locale.

Custom events on the key funnel:
- demo-request (demo form submit, with teamSize)
- partner-application (partner form submit, with type)
- book-demo (every "Book a demo" CTA click) via data-umami-event
- login (clicks through to the app)

Also fix the mobile nav menu links, which weren't localized (would drop
Danish visitors back to English).

apps/website/components/landing/FinalCta.vue

@@ -21,7 +21,7 @@ const localePath = useLocalePath()
       </h2>
       <div :style="{ marginTop: '28px', maxWidth: 'min(100%, 520px)', fontFamily: '\'Inter\', sans-serif', fontSize: '19px', color: 'rgba(244,243,238,0.7)' }">{{ copy.finalCta.sub }}</div>
       <div :style="{ marginTop: '40px' }">
-        <button @click="navigateTo(localePath('/demo'))" :style="{
+        <button data-umami-event="book-demo" @click="navigateTo(localePath('/demo'))" :style="{
           background: C.signal, color: C.carbon, border: 'none',
           padding: '20px 32px', fontFamily: '\'Inter\', sans-serif',
           fontSize: '16px', fontWeight: 600, borderRadius: '4px', cursor: 'pointer',