Add Catena-X example with external PostgreSQL and EDC UI configuration

[antesch]

Summary

This PR addresses #75 by adding a Catena-X oriented BaSyx Go Helm chart example and extending the chart with support for existing external PostgreSQL databases.

It also configures the AAS Web UI for CatenaXplorer/EDC use cases and documents the end-to-end Catena-X setup.

Changes

• Add values/values.catena-x.example.yaml for a Catena-X oriented deployment.
• Configure Digital Twin Registry and Submodel Repository for marker-based ABAC.
• Configure Keycloak demo users for provider and partner access scenarios.
• Configure AAS Web UI with the catena-x infrastructure template.
• Add CatenaXplorer EDC UI runtime settings based on the upstream AAS Web UI CatenaXplorerEdcStandalone example.
• Add Secret-based AAS Web UI environment support via aasWebGui.secretEnvironment and aasWebGui.existingSecretEnvironment.
• Add support for database.type=external to use an existing PostgreSQL database instead of rendering a CloudNativePG cluster.
• Add values/values.external-db.example.yaml for external PostgreSQL deployments.
• Keep the existing managed CloudNativePG database mode as the default for backwards compatibility.
• Add support for service-specific database overrides, so individual BaSyx Go backend services can use their own external PostgreSQL Secret or inline database configuration.
• Add support for advanced external PostgreSQL options such as sslmode, sslcert, sslkey, sslrootcert, connectTimeoutSeconds, applicationName, fallbackApplicationName, searchPath, options, and timezone.
• Render optional PostgreSQL Secret keys as optional POSTGRES_* environment variables for BaSyx Go backend services.
• Generate JDBC URLs with PostgreSQL parameters for inline external database values, including sslmode and currentSchema derived from searchPath.
• Ensure Keycloak uses KC_DB=postgres while still reading its JDBC URL from the selected database Secret.
• Disable the Configuration Service database wait initContainer in the external DB example overlay, because external databases are usually managed independently.
• Document external PostgreSQL usage, Secret requirements, optional PostgreSQL settings, inline test values, service-specific database overrides, and Catena-X setup.
• Add Helm unit tests for Catena-X ABAC, UI configuration, EDC UI environment, external database wiring, service-specific database overrides, advanced PostgreSQL options, and schema validation.

Validation

helm lint charts/basyx -f values/values.catena-x.example.yaml
helm lint charts/basyx -f values/values.external-db.example.yaml
helm lint charts/basyx -f values/values.catena-x.example.yaml -f values/values.external-db.example.yaml
helm unittest charts/basyx

[th0masgl]

i think you can also disable the waitfordb initcontainers if you want to use an external database and add that to values/values.external-db.example.yaml

And i can not connect to the external database, i guess because i can not pass sslmode=require and searchpath=myschema