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.

gradle.properties

@@ -33,7 +33,7 @@ org.gradle.parallel=true
 org.gradle.caching=true
 
 # Security and Reproducibility
-org.gradle.dependency.verification=lenient
+org.gradle.dependency.verification=strict
 org.gradle.dependency.locking.enabled=true
 
 # Development