ci: fix docs-only detection by inverting to has-code filter

[zackverham]

Summary

Fixes docs-only detection which was completely broken due to issues with dorny/paths-filter's predicate-quantifier feature.

Problems Found

1. Missing input definition: The predicate-quantifier input isn't declared in action.yml for v3, causing "Unexpected input" warnings

   • Original feature PR: dorny/paths-filter#224 - added code but missed action.yml
   • Fix PR merged but not released: dorny/paths-filter#279
   • Open issues about this: #226, #236, #259

2. Broken implementation: Even when the input is accepted, the implementation is wrong:

   • Expected: "Return true if ALL changed files match at least one pattern"
   • Actual: "A file matches only if it matches ALL patterns" (L110-111: patterns.every(aPredicate) checks if a single file matches every pattern)

   This meant CHANGELOG.md was rejected because it doesn't match LICENSE, .gitignore, etc.

Solution

Invert the logic from detecting "docs-only" to detecting "has-code":

# Old (broken): docs-only is true if ALL files are docs
docs-only:
  - '**/*.md'
  - 'LICENSE'
  # predicate-quantifier: every  # broken!

# New (works): has-code is true if ANY file is NOT a doc
code:
  - '**'
  - '!**/*.md'
  - '!LICENSE'
  - '!.gitignore'
  - '!.gitattributes'

With the default some quantifier:

• has-code = true if any file matches (i.e., any non-doc file exists)
• CI runs when has-code == 'true'
• CI skips when only doc files changed

Test plan

• PRs with only .md file changes skip tests
• PRs with code changes run tests
• No more "Unexpected input" warnings

🤖 Generated with Claude Code