feat(command-development): add scripts/ directory with validation utilities

[sjnims]

Summary

The command-development skill lacks a scripts/ directory with utility scripts, unlike the hook-development skill which provides helpful validation tools (validate-hook-schema.sh, test-hook.sh, hook-linter.sh).

Current State

command-development/
├── SKILL.md
├── examples/
│   ├── plugin-commands.md
│   └── simple-commands.md
└── references/
    └── (9 reference files)

Proposed Addition

command-development/
├── SKILL.md
├── examples/
├── references/
└── scripts/
    ├── validate-command.sh      # Validate command file structure
    └── check-frontmatter.sh     # Validate YAML frontmatter

Context

The references/testing-strategies.md file already includes inline script examples for command validation:

• YAML frontmatter validation
• File structure validation
• Frontmatter field validation

These could be extracted into actual executable scripts for users to run directly.

Benefits

1. Users can validate commands before deployment
2. Consistent with hook-development skill pattern
3. Scripts are token-efficient (can be executed without loading into context)
4. Improves developer experience

Acceptance Criteria

• Create scripts/ directory
• Add validate-command.sh - validates command file structure
• Add check-frontmatter.sh - validates YAML frontmatter fields
• Scripts should be executable (chmod +x)
• Update SKILL.md to reference new scripts in "Additional Resources" section

[sjnims]

PR submitted: #63