feat: link login/register buttons to app.armarium.ch (v0.8.1)

All hero, CTA, and footer login/register buttons now point to
https://app.armarium.ch/login and https://app.armarium.ch/register.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/landing/AboutPage.astro

@@ -154,7 +154,7 @@ const t = useTranslations(locale);
       <h2 class="font-display text-4xl font-bold text-foreground mb-4 text-balance">{t('about.cta.title')}</h2>
       <p class="text-lg text-foreground-muted mb-8 text-balance">{t('about.cta.desc')}</p>
       <div class="flex flex-col sm:flex-row gap-4 justify-center">
-        <Button size="lg" href="/register">
+        <Button size="lg" href="https://app.armarium.ch/register">
           {t('cta.register')}
           <Icon name="arrow-right" size="sm" />
         </Button>