v0.13.1

• Add cross-language CLI version helpers that run before application parsers so explicit --version --output json|yaml|plain emits a standardized {code:"version", version} AFDATA event
• Preserve conventional bare --version text by default while documenting VersionConfig::conventional_default() as the recommended Rust preset for first-party CLIs
• Document the Agent-First CLI version-output contract across the spec, skill, overview, and language READMEs so downstream afdata users can adopt the same behavior