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/pages/partners.vue

@@ -1,6 +1,6 @@
 <script setup lang="ts">
 import { ref } from 'vue'
-import { useTheme, useCopy } from '~/composables/useLanding'
+import { useTheme, useCopy, track } from '~/composables/useLanding'
 
 definePageMeta({ layout: 'page' })
 
@@ -35,6 +35,7 @@ function submitPartner() {
     '',
     pMessage.value,
   ].join('\n')
+  track('partner-application', { type: pType.value })
   window.location.href = `mailto:info@dezky.eu?subject=${encodeURIComponent(subject)}&body=${encodeURIComponent(body)}`
 }
 
@@ -197,7 +198,7 @@ useHead({ title: () => `${copy.value.pages.partners.label} · dezky` })
           <p :style="{ marginTop: '20px', fontFamily: '\'Inter\', sans-serif', fontSize: '18px', lineHeight: 1.6, color: t.fgMuted, maxWidth: '420px', textWrap: 'pretty' }">{{ c.form.lede }}</p>
           <button
             :style="{ marginTop: '28px', background: 'transparent', border: 'none', padding: 0, cursor: 'pointer', fontFamily: '\'Inter\', sans-serif', fontSize: '15px', color: t.fgMuted, textDecoration: 'underline', textUnderlineOffset: '3px' }"
-            @click="navigateTo(localePath('/demo'))"
+            data-umami-event="book-demo" @click="navigateTo(localePath('/demo'))"
           >{{ c.cta }} →</button>
         </div>