iac/helmify: ingress, validation, secrets

[ranchodeluxe]

Changes

• add kind: Ingress (no domains or TLS)
• use shared Ingress for saving 💰 with path-based routing
• os environment variables pass through to secrets
• validation of values.yaml

[batpad]

@ranchodeluxe have left small comments, but none of them are blockers - this looks really great to me.