Problem #1221

Problem

Root coordination.k9 does not parse under its own normative grammar,
2-protocols/k9-coordination/spec/abnf/coordination-k9-grammar_v1.1.abnf.

This predates the 9-archive move. During that work two entries were added to
its protected: section (a new 9-archive/ entry, and a rewritten reason for
the residual rhodium-standard-repositories/ entry); both parse in isolation.
The file as a whole still does not.

Why it matters

• 2-protocols/k9-coordination/README.adoc states plainly: "No validator
  script exists yet, and a generic YAML parser does not conform." So nothing
  catches this.
• The repo is the reference implementation of the format it defines —
  coordination.k9 says so in its own header. The one file that must conform
  does not.

Acceptance

• A validator for coordination.k9 exists and runs in CI.
• Root coordination.k9 parses under the v1.1 ABNF.
• A planted defect in coordination.k9 is rejected by the validator.