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/Pricing.vue

@@ -18,7 +18,7 @@ const localePath = useLocalePath()
             <p :style="{ fontFamily: '\'Inter\', sans-serif', fontSize: '20px', lineHeight: 1.5, maxWidth: '640px', color: t.fgMuted, margin: 0, textWrap: 'pretty' }">{{ copy.pricing.lede }}</p>
           </div>
           <div :style="{ marginTop: '36px', display: 'flex', alignItems: 'center', gap: '16px' }">
-            <LandingBtn variant="primary" size="lg" @click="navigateTo(localePath('/demo'))">{{ copy.pricing.cta }} →</LandingBtn>
+            <LandingBtn variant="primary" size="lg" data-umami-event="book-demo" @click="navigateTo(localePath('/demo'))">{{ copy.pricing.cta }} →</LandingBtn>
           </div>
         </div>
         <div :style="{ background: t.surface, border: `1px solid ${t.border}`, borderRadius: '6px', padding: '36px 36px' }">