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/Nav.vue

@@ -97,8 +97,8 @@ function segStyle(code: 'en' | 'da') {
           <button :style="segStyle('en')" @click="switchTo('en')">EN</button>
           <button :style="segStyle('da')" @click="switchTo('da')">DA</button>
         </div>
-        <a :href="APP_URL" :style="{ fontFamily: '\'Inter\', sans-serif', fontSize: '14px', color: t.fgMuted }">{{ copy.nav.login }}</a>
-        <LandingBtn variant="primary" @click="navigateTo(localePath('/demo'))">{{ copy.nav.cta }} →</LandingBtn>
+        <a :href="APP_URL" data-umami-event="login" :style="{ fontFamily: '\'Inter\', sans-serif', fontSize: '14px', color: t.fgMuted }">{{ copy.nav.login }}</a>
+        <LandingBtn variant="primary" data-umami-event="book-demo" @click="navigateTo(localePath('/demo'))">{{ copy.nav.cta }} →</LandingBtn>
       </div>
 
       <!-- Hamburger — visible only on mobile via scoped CSS -->
@@ -147,7 +147,7 @@ function segStyle(code: 'en' | 'da') {
       }"
     >
       <NuxtLink
-        v-for="(it, i) in items" :key="i" :to="it.href"
+        v-for="(it, i) in items" :key="i" :to="loc(it.href)"
         :style="{
           fontFamily: '\'Inter\', sans-serif', fontSize: '16px', color: t.fgMuted,
           letterSpacing: '-0.005em', padding: '14px 0',
@@ -164,10 +164,11 @@ function segStyle(code: 'en' | 'da') {
         </div>
         <a
           :href="APP_URL"
+          data-umami-event="login"
           :style="{ fontFamily: '\'Inter\', sans-serif', fontSize: '14px', color: t.fgMuted }"
           @click="mobileOpen = false"
         >{{ copy.nav.login }}</a>
-        <LandingBtn variant="primary" @click="() => { navigateTo(localePath('/demo')); mobileOpen = false }">{{ copy.nav.cta }} →</LandingBtn>
+        <LandingBtn variant="primary" data-umami-event="book-demo" @click="() => { navigateTo(localePath('/demo')); mobileOpen = false }">{{ copy.nav.cta }} →</LandingBtn>
       </div>
     </div>
   </header>