fable-validate

Use when the user wants a GitHub issue validated by a Fable 5.1 subagent. Spins up a read-only subagent running on Fable 5.1 that executes the validate-issue procedure (claim tracing, architecture/consistency checks, complexity score), then relays the verdict back to the main agent, which presents it and takes any follow-on action (update issue, work on issue). Trigger on "/fable-validate", "fable validate <issue>",…