OUTPUT FORMAT:

  Single markdown document with inlined content:

    # Main Document

    Introduction text...

    ## Referenced Section

    Content from referenced document, headers adjusted down one level.

    ### Nested Reference

    Content from second-level reference, headers adjusted accordingly.

  Header levels are automatically adjusted to maintain hierarchy when
  content is inlined. The output preserves document structure while
  combining multiple files.

EXAMPLES:

  # Squash with default depth (2 levels)
  iwe squash project-overview

  # Shallow squash (direct references only)
  iwe squash index --depth 1

  # Deep squash (follow all references)
  iwe squash main --depth 5

  # Export to single file
  iwe squash documentation > full-docs.md
