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/ExperiencePage.astro

@@ -0,0 +1,26 @@
+---
+import type { Locale } from '@i18n/locales';
+import { useDict } from '@i18n/t';
+import Base from '@layouts/Base.astro';
+import { getMeta } from '@lib/content';
+import SectionLabel from '@components/ui/SectionLabel.astro';
+import ExperienceTimeline from '@components/home/ExperienceTimeline.astro';
+
+interface Props {
+  locale: Locale;
+}
+const { locale } = Astro.props;
+const d = useDict(locale);
+const m = getMeta('experience', locale);
+---
+
+<Base locale={locale} pageId="experience" title={m.title} description={m.description}>
+  <div class="mx-auto max-w-[--content-max] px-6 pt-14">
+    <SectionLabel text={d.home.experienceLabel} />
+    <h1 class="mt-4 text-h1">{d.home.experienceHeading}</h1>
+    <p class="mt-4 max-w-[62ch] text-body-lg text-ink-muted">{m.description}</p>
+  </div>
+  <div class="mt-8">
+    <ExperienceTimeline locale={locale} eyebrow={false} />
+  </div>
+</Base>