Module formatter 

Formatter: converts a Schema AST back to canonical .nautilus source text.

• 2-space indentation
• Blank lines between top-level blocks
• Column spacing of 1 (padding = max_width - len + 1)
• Field name column always padded (even for fields with no attributes)
• Field type column padded only for fields that have attributes
• Single space between attributes on the same field
• Key-value pairs in datasource/generator blocks are aligned
• Blank lines between field groups are preserved (detected via spans)
• Blank line inserted before model-level @@ attributes
• Comments are preserved (both inline trailing comments and standalone comment lines)

Functions

format_schema

Format a Schema AST back to canonical .nautilus source text.