eval-authoring-skill

Author and validate Vally evals for Agent Skills under .github/skills. WHEN: "write a skill eval", "add trigger eval", "test skill routing", "add anti-trigger tests", "create skill capability eval", "harden skill graders". DO NOT USE FOR: single MCP tool prompt-to-tool coverage (use eval-authoring-tool), multi-tool or multi-turn scenarios (use eval-authoring-workflow), authoring SKILL.md itself (use skill-authoring).