integration: add route metadata, JSON-LD and harden the public shell

Ship prerendered SEO, crawl files and palette/map a11y so every locale route is indexable, honest and keyboard-usable without inventing claims.

Co-authored-by: Cursor <cursoragent@cursor.com>

public/llms.txt

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+# Antonio Ledebuhr
+
+Fullstack and DevOps engineer in Tangermünde. The public site documents a curated set of stations, four service areas, and a local mailto briefing. German is the default language; English is the full second version.
+
+## Profile
+
+- https://antoniolede.de/
+- https://antoniolede.de/en
+- https://antoniolede.de/ueber-mich
+- https://antoniolede.de/en/about
+
+## Services
+
+- https://antoniolede.de/leistungen
+- https://antoniolede.de/en/services
+- https://antoniolede.de/leistungen/software
+- https://antoniolede.de/en/services/software
+- https://antoniolede.de/leistungen/hardware-netzwerk
+- https://antoniolede.de/en/services/hardware-network
+- https://antoniolede.de/leistungen/cluster
+- https://antoniolede.de/en/services/clusters
+- https://antoniolede.de/leistungen/ai-integration
+- https://antoniolede.de/en/services/ai-integration
+
+## Projects
+
+- https://antoniolede.de/projekte
+- https://antoniolede.de/en/projects
+- https://antoniolede.de/projekte#innofocus
+- https://antoniolede.de/en/projects#innofocus
+- https://antoniolede.de/projekte#roesterei
+- https://antoniolede.de/en/projects#roesterei
+- https://antoniolede.de/projekte#myspa
+- https://antoniolede.de/en/projects#myspa
+- https://antoniolede.de/projekte#hdi
+- https://antoniolede.de/en/projects#hdi
+
+## Contact, stack and legal
+
+- https://antoniolede.de/kontakt
+- https://antoniolede.de/en/contact
+- https://antoniolede.de/stack
+- https://antoniolede.de/en/stack
+- https://antoniolede.de/impressum
+- https://antoniolede.de/en/legal-notice
+- https://antoniolede.de/datenschutz
+- https://antoniolede.de/en/privacy
+
+## Languages
+
+German URLs are unprefixed. English URLs live under `/en`. Each public page exists in both locales.