fix: include comment env fields in build responses

[vigneshrajsb]

Summary

• Return commentRuntimeEnv and commentInitEnv from v2 build response queries.
• Align v1, v2, and service-level build UUID validation around one shared lowercase/Kubernetes-safe format validator.
• Document the build UUID length and lowercase pattern on the OpenAPI build patch schema.
• Add regression coverage for build detail/list response fields, UUID format validation, service-level UUID validation, and OpenAPI schema shape.