Vendor Inter (variable + italic, OFL) under assets/fonts/inter/ and make it
the default application UI face, replacing Josefin Sans (which stays bundled
as a selectable option). pubspec font family + licenses.yaml entry per D-42.
Settings → Appearance gains a UI-font select (Inter / Josefin Sans). The root
DefaultTextStyle reads app.ui.font (kUiFontSettingKey) over the default and
re-applies live on settings change, so a pick takes effect immediately. Bump
the default UI weight to w400 — Inter reads better at Regular than Josefin's
Light.
The monospace picker is deferred to T-471: clideMonoFamily is a const at ~38
call sites (not inherited), so a live mono picker needs the family routed
through context first.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>