fix: resolve SKILL.md validation errors

skills/using-git-worktrees/SKILL.md

@@ -1,6 +1,8 @@
 ---
 name: using-git-worktrees
 description: "Use when starting feature work that needs isolation from current workspace or before executing implementation plans - creates isolated git worktrees with smart directory selection and safety verifi..."
+risk: unknown
+source: community
 ---
 
 # Using Git Worktrees
@@ -215,3 +217,6 @@ Ready to implement auth feature
 **Pairs with:**
 - **finishing-a-development-branch** - REQUIRED for cleanup after work complete
 - **executing-plans** or **subagent-driven-development** - Work happens in this worktree
+
+## When to Use
+This skill is applicable to execute the workflow or actions described in the overview.