infra: clean up Keycloak configuration, enforce consistency in .env, and improve health checks

Streamlined Keycloak configurations with defaults for development and production in `.env`. Added health checks and improved environment variable documentation with comments to differentiate local and server deployments. Ensured compatibility with pre-built registry images.

docs/07_Infrastructure/Reference/ports-and-urls.md

@@ -1,6 +1,7 @@
 ---
-owner: project-maintainers
-status: active
+type: Reference
+owner: DevOps Engineer
+status: ACTIVE
 review_cycle: 180d
 last_reviewed: 2025-10-31
 summary: "Übersicht der wichtigsten lokalen URLs und Ports. Quelle: docker-compose.yaml + config/env"

docs/07_Infrastructure/Reference/zipkin.md

@@ -1,3 +1,8 @@
+---
+type: Reference
+status: ACTIVE
+owner: DevOps Engineer
+---
 # Zipkin Tracing
 
 ## Übersicht