chore: update agentskills rules paths and eslint ignore

- Add paths frontmatter to agentskills.md for skill file matching
- Add ref/** to eslint ignore patterns

Author: amondnet

.claude/rules/agentskills.md

@@ -1,3 +1,7 @@
+---
+paths: skills/**/*, .claude/skills/**/*
+---
+
 # Agent Skills
 
 ## Docs

eslint.config.js

@@ -11,6 +11,7 @@ export default antfu({
     '.please/memory/**',
     'specs/**',
     'docs/**',
+    'ref/**',
   ],
 }, {
   rules: {