Agent Skills: fa-testing

Provides Gaia's formal validation guidance across unit, integration, manual regression, automated regression, and evidence review. Use it by running the test layers required by each task's gates (unit → integration → e2e → manual regression), recording proof labels (e.g. 'curl', 'playwright-mcp') on tasks_complete, and vetoing completion when evidence is missing. Use it when a branch is stable enough for hardening, when high-risk behavior needs targeted early validation, or when release readiness depends on a clear QA signal.