Add linting and validation CLI commands

[akonan]

Description

Provide linting and validation commands for wiremd files.

Features

Lint Command

wiremd lint mockup.md

• Check syntax errors
• Validate component usage
• Check best practices
• Suggest improvements
• Configurable rules

Validate Command

wiremd validate mockup.md --strict

• Schema validation
• Type checking
• Accessibility checks
• Required field validation

Fix Command

wiremd lint mockup.md --fix

• Auto-fix common issues
• Format code
• Add missing attributes

Priority

Medium

Labels

enhancement, cli, linting, validation