i18n copy & layout

The expensive i18n bugs aren't missing translations — they're the layout, grammar, and formatting assumptions baked in while the app was English-only, which surface only when real translated copy lands. Core rule: treat copy as variable-length, variable-order, variable-form data, never as fixed text measured once in English. Two halves: copy (the words and values) and layout (the space they live in).

For East-Asian glyph rendering, line-breaking (word-break: keep-all), and IME composition, use cjk-text-and-input — the two are deliberately split.

Checklist (lead with the trap; details in references/)

Layout → layout