Adds a "Statistik" cookie category (alongside the existing external
media one), an admin-configurable Measurement ID field in Website
Settings, and a GoogleAnalytics component that only injects gtag.js
after the visitor has consented - mirrors the existing ExternalEmbed
pattern instead of loading tracking scripts unconditionally.
Also documents Google Analytics in the Datenschutzerklärung (new
section 8, remaining sections renumbered) since introducing a new
data processing purpose requires disclosure.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
