Function render_codex32_grouped 

pub fn render_codex32_grouped(s: &str, group_size: usize) -> String

Render a codex32 string with optional N-char HYPHEN grouping for transcription aid (spec §10.2). group_size = 0 returns the input unchanged. Back-compat wrapper over render_grouped (hyphen separator). Retained as public API (documented in the technical manual); new callers use render_grouped with an explicit separator.