Settings → Appearance gains a Monospace font select (JetBrains Mono / Fira
Mono) on the schema engine, writing app.mono.font. It applies live: root_shell
resolves the family into the ClideSettingsScope (D-101) and rebuilds on the
settings change, so the ~93 migrated mono sites — terminal, diffs, code, IDs —
re-read the new family at once.
Vendor Fira Mono (Regular + Bold, OFL) under assets/fonts/fira_mono/ with the
pubspec font family + licenses.yaml entry per D-42; JetBrains Mono stays the
default.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>