feat: add dart_skills_lint reusable workflow

[very-good-code-bot]

Summary

Adds a new reusable workflow for validating agent skill directories using the dart_skills_lint tool. This workflow performs static analysis checks to ensure skill definitions comply with the Agent Skills Specification.

Changes

• Added .github/workflows/dart_skills_lint.yml reusable workflow with workflow_call trigger
• Configurable inputs for:
  • skills_directories: Space-separated list of skill root directories (defaults to .claude/skills and .agents/skills)
  • dart_skills_lint_version: Version constraint for the tool (defaults to latest)
  • dart_sdk: Dart SDK version (defaults to stable)
  • runs_on: Runner environment (defaults to ubuntu-latest)
  • working_directory: Working directory (defaults to .)
• Workflow steps:
  1. Checkout code
  2. Setup Dart SDK
  3. Activate dart_skills_lint
  4. Run skill validation with configured directories
• Updated README.md with workflow documentation

Validation

This workflow serves as a presubmit check for skill definitions, validating:

• SKILL.md file presence and structure
• YAML frontmatter compliance
• Directory structure integrity
• Relative path validity

Closes #449

[marcossevilla]

@vgvbot check ci failures and try to fix them

[very-good-code-bot]

On it, I'll address the review comments and push the changes.

• Preparing environment
  • Cloning repository
  • Setting up dev environment
• Reviewing feedback
• Working on changes
• Pushing updates

I've pushed changes to address the feedback.

[marcossevilla]

@vgvbot formatting is still failing for docs/workflows/dart_skills_lint.md. use prettier to fix this.

[very-good-code-bot]

On it, I'll address the review comments and push the changes.

• Preparing environment
  • Cloning repository
  • Setting up dev environment
• Reviewing feedback
• Working on changes
• Pushing updates

I've pushed changes to address the feedback.

[marcossevilla]

@vgvbot also add a workflow to verify this new reusable workflow you introduced, take inspiration in verify-dart

[very-good-code-bot]

On it, I'll address the review comments and push the changes.

• Preparing environment
  • Cloning repository
  • Setting up dev environment
• Reviewing feedback
• Working on changes
• Pushing updates

I've pushed changes to address the feedback.

[marcossevilla]

@vgvbot fix the failing ci workflow by activating dart_skills_lint as a git ref dependency

[very-good-code-bot]

On it, I'll address the review comments and push the changes.

• Preparing environment
  • Cloning repository
  • Setting up dev environment
• Reviewing feedback
• Working on changes
• Pushing updates

I've pushed changes to address the feedback.