Function resolve_column_name 

pub fn resolve_column_name<'a>(
    input: &str,
    available: &[&'a str],
) -> Result<&'a str, ColumnResolveError>

Resolves a column name against a list of available columns with case-insensitive fallback.

1. Exact match — returns the name unchanged.
2. Unique case-insensitive match — returns the actual column name from available.
3. Ambiguous (multiple case-insensitive matches) — returns Err listing all matches.
4. No match — returns Err with an edit-distance suggestion if one is close enough.

Errors

Returns ColumnResolveError::NotFound when no column matches, or ColumnResolveError::Ambiguous when multiple columns match case-insensitively.