As decided in #432 (option 2): while the interface is in Japanese, new type starts with em box
top-to-top leading and em box centre character alignment; other languages keep the Roman
baseline, so Latin area type doesn't move.
- The UI tells the engine the language it is drawn in each frame (`Session::ui_language`); without
a UI, an explicit `interfaceLanguage` preference counts (`Session::japanese_interface`).
- `text.create` and `text.createInPath` (the Type tools' clicks and drags) apply it, and take
`leadingModel` / `charAlign` to choose; the values used are journaled, so a replay does the same
in any language.
- `paraStyle.new` / `charStyle.new` made from nothing (no `attrs`, no text selected) carry them.
- Imported text (PDF, SVG, DXF…) keeps the Roman baseline. Saved documents keep what they say.
- docs/mcp.md (New type in a Japanese interface) and the ROADMAP note it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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