[2.15.2] Fix skill spec compliance across all skills

Fixed issues flagged by skill-creator spec:
- Reference files now use proper markdown links instead of backtick text
- Descriptions use third person ("This skill should be used when...")
- Added Skill Compliance Checklist to CLAUDE.md with validation commands

Affected skills: agent-native-architecture, andrew-kane-gem-writer,
compound-docs, create-agent-skills, dhh-rails-style, dhh-ruby-style,
dspy-ruby, every-style-editor, file-todos, frontend-design, gemini-imagegen

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/compound-engineering/skills/file-todos/SKILL.md

@@ -40,7 +40,7 @@ Todo files follow this naming pattern:
 
 ## File Structure
 
-Each todo is a markdown file with YAML frontmatter and structured sections. Use the template at `assets/todo-template.md` as a starting point when creating new todos.
+Each todo is a markdown file with YAML frontmatter and structured sections. Use the template at [todo-template.md](./assets/todo-template.md) as a starting point when creating new todos.
 
 **Required sections:**
 - **Problem Statement** - What is broken, missing, or needs improvement?