Function replace_one_query 

pub fn replace_one_query(
    buffer: &mut EditorBuffer,
    query: &SearchQuery,
    range: Range<usize>,
    replacement: &str,
) -> Result<bool, EditorError>

Replaces the single match range with replacement (undoable).

Returns Ok(false) without touching the buffer when range is empty, out of bounds, or not a current match of query. Regex replacements expand $1 / $name captures.