Validate generated workflows

[nickbeau]

Detail: Validate generated workflow settings and required secret references before provisioning.

Milestone: Sprint 6: Symphony Release Resolver and Workflow Generator

Source: docs/technical.md sprint plan.

[nickbeau]

I’m starting work on this issue. I’ll inspect the workflow-related domain/application code and sprint requirements, then add validation for generated workflow settings and required secret references with focused tests and documentation updates before opening a PR.