Rust ZITADEL-compatible identity platform

Build a production-grade Rust replacement for the ZITADEL deployment based on production branch `feat/nb-translations` at commit `4877cddfba02c3fed166a35e19927360dd8467fe`. Reuse the existing PostgreSQL database in place without a schema or data migration, expose the OIDC and v2 API subset required by moeteadm, and replace the JavaScript-heavy login/admin applications with localized Askama server rendering in English (`en`), Norwegian Bokmål (`nb`), and Danish (`da`). Use Stimulus only for progressive enhancement and browser-only capabilities such as WebAuthn. Delivery uses a rehearsed hard cutover with secure rollback; it is not an MVP or disposable prototype.