Feature Request: Index File Refactoring Support

[Mearman]

Feature Request: Index File Refactoring Support

Problem

Currently, markmv supports moving, splitting, joining, and generating documentation indexes, but lacks functionality to refactor content between different index file types (e.g., README.md ↔ index.md).

Proposed Solution

Add functionality to support refactoring between different index files with automatic link updates and content preservation.

Use Cases

1. README.md to index.md: Convert project README files to index files for documentation systems
2. index.md to README.md: Convert documentation index files back to standard README format
3. Cross-format migration: Support migration between different documentation conventions

Suggested Implementation

• Add refactorIndex() function with source/target file type detection
• Maintain all existing link updating capabilities
• Preserve content structure and formatting
• Handle metadata and frontmatter appropriately
• Support bidirectional conversion

Example Usage

// Convert README.md to index.md
await refactorIndex('README.md', 'index.md');

// Convert index.md to README.md  
await refactorIndex('index.md', 'README.md');

Additional Context

This would complement the existing file operations and documentation generation features, providing a complete solution for documentation file management across different naming conventions and project structures.