Validate SKILL.md frontmatter and .feature-radar/ files against format rules. Runs
validate.sh, reports errors/warnings, and auto-fixes issues. MUST use this skill after
editing any SKILL.md or .feature-radar/ file, even if the user doesn't ask — catches format
bugs like the Agent Skills spec's 1024-char description limit before they break the skill.
Use when the user asks to validate, lint, or verify skills or .feature-radar/ files, after
editing either, or before committing changes that touch skills/ or .feature-radar/.
