//! Rendering primitives: text engine, UI draw helpers, e-ink constants.
//!
//! - [`text_render`] — HarfBuzz shaping + fontdue rasterization → RGB565
//! - [`common`] — shared rendering state (`IS_RTL`) and body-text size constant
//! - [`layout`] — `word_wrap_bytes()` and `sentences_with_ranges()` (pure text)
//! - [`draw`] — progress bars, rounded rects, nav bars (RGB565 byte-buffer ops)
//! - [`eink`] — MXCFB ioctl structs, waveform constants, `diff_rows()`