feat: German as the main language, English under /en, with a language switch

The site now exists in German (at the root, with /impressum and /datenschutz)
and English (/en). A request without a language follows the visitor's choice
from the language switch, then the browser language, then German; the old
English legal addresses move to /en for good.

All visible texts are data in src/content/de.ts and en.ts, so components hold
none of their own. The header carries a DE/EN switch whose bit curtain covers
the page while it is swapped and reopens at the same reading position. Title,
description, canonical, hreflang, Open Graph, the share image, the sitemap and
the structured data are per language. The privacy notice now describes the
cookie that remembers the chosen language.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/src/content/site.ts

@@ -1,17 +1,12 @@
 import { parseEmailParts, type EmailParts } from "@/src/domain/email";
 import { indexingFor } from "@/src/domain/indexing";
 
+// What is the same in every language. Titles, descriptions and all other texts
+// live in en.ts and de.ts.
+
 export const SITE_NAME = "Marc Mintel";
 export const SITE_URL = "https://mintel.me";
 
-/** One wording for the browser title, search results and link previews. */
-export const SITE_TITLE =
-  "Freelance web developer for web apps & websites | Marc Mintel";
-export const SITE_DESCRIPTION =
-  "Freelance web developer with 15 years of experience. I build web apps, interfaces and websites with React, Next.js and TypeScript, and automate processes.";
-export const SITE_LANGUAGE = "en";
-export const JOB_TITLE = "Freelance web developer";
-
 /**
  * Public profiles of the owner (LinkedIn, GitHub, ...). Search engines use them to
  * connect this site with the same person elsewhere. Only add profiles the owner confirmed.
@@ -39,7 +34,8 @@ export const CONTACT_EMAIL_PARTS: EmailParts = parsedEmail.value;
 export const OWNER = {
   name: "Marc Mintel",
   street: "Georg-Meistermann-Straße 7",
-  city: "54586 Schüller",
-  country: "Germany",
+  postalCode: "54586",
+  locality: "Schüller",
+  countryCode: "DE",
   vatId: "DE367588065",
 } as const;