feat: Content-type aware frontmatter rules

[markcheret]

Description

Implement different frontmatter validation rules based on content type (blog posts vs documentation vs API references).

Requirements

• Path-based content type detection
• Different validation profiles per content type:
  • Blog posts: require date, author, tags, description, image
  • Documentation: require description, tags (optional)
  • API references: require version, endpoint type
  • Tutorials: require difficulty, duration, tags
• Support custom content type definitions via config

Use Cases

• Multi-section documentation sites (docs + blog + API)
• Different SEO requirements per content type
• Enforce editorial standards by section

Suggested Implementation

• Extend path_overrides with named content type profiles
• Inheritance model (content types extend base rules)
• Clear error messages indicating content type expectations

Example Configuration

content_types:
  blog:
    paths: ["blog/posts/**"]
    frontmatter:
      required: ["date", "author", "description", "tags"]
      description:
        min_length: 155
        max_length: 160
  
  docs:
    paths: ["docs/**"]
    frontmatter:
      required: ["description"]
      description:
        min_length: 100
        max_length: 200

Related

Foundation for implementing all other frontmatter validations with proper context awareness.