feat: case-study template, all pages, routing, sitemap, 404

- case-study components: CsHeader, TldrBox, MiniToc, SectionRenderer, DecisionList,
  ArchDiagram (data-driven), Gallery, NextPrev, CaseStudyPage
- standalone pages: projects index, about, experience, contact (with form),
  cv hub, colophon — all EN/NO compositions
- full route tree: EN root + /no localised slugs (prosjekter, om-meg, erfaring,
  kontakt, kolofon, hjemmelab) per ROUTING_SPEC
- bilingual 404 with trace-fray motif; robots.txt + sitemap.xml from slug map
- Portrait atom; reusable sections gain header/eyebrow toggles for standalone pages

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

site/src/components/pages/AboutPage.astro

@@ -0,0 +1,48 @@
+---
+import type { Locale } from '@i18n/locales';
+import { useDict } from '@i18n/t';
+import Base from '@layouts/Base.astro';
+import { getProfile, getMeta } from '@lib/content';
+import SectionLabel from '@components/ui/SectionLabel.astro';
+import Portrait from '@components/ui/Portrait.astro';
+
+interface Props {
+  locale: Locale;
+}
+const { locale } = Astro.props;
+const d = useDict(locale);
+const profile = getProfile(locale);
+const m = getMeta('about', locale);
+---
+
+<Base locale={locale} pageId="about" title={m.title} description={m.description} ogType="profile">
+  <div class="mx-auto grid max-w-[--content-max] gap-12 px-6 py-14 lg:grid-cols-12">
+    <div class="lg:col-span-7">
+      <SectionLabel text={d.nav.about} />
+      <h1 class="mt-4 text-h1">{profile.aboutHeading}</h1>
+      <div class="mt-6 flex flex-col gap-4">
+        {profile.aboutParagraphs.map((para) => <p class="max-w-[64ch] text-body-lg text-ink-muted">{para}</p>)}
+      </div>
+      <p class="mt-8">
+        <span class="mono-label mb-2 block">{d.about.interests}</span>
+        <span class="text-body text-ink-muted">{profile.interestsLine}</span>
+      </p>
+    </div>
+
+    <aside class="lg:col-span-5">
+      <Portrait src={profile.photo.src} alt={profile.photo.alt} caption={profile.photo.caption} />
+      <div class="mt-8">
+        <p class="mono-label mb-3">{d.about.languages}</p>
+        <ul class="flex flex-col gap-2">
+          {
+            profile.languages.map((lang) => (
+              <li class="text-body text-ink">
+                {lang.label} <span class="text-ink-muted">— {lang.level}</span>
+              </li>
+            ))
+          }
+        </ul>
+      </div>
+    </aside>
+  </div>
+</Base>