#2237 named the Sure font families (SureTokens.fontSans 'Geist', fontMono
'Geist Mono') from design/tokens/sure.tokens.json but deferred bundling the
fonts, so the app declared fontFamily 'Geist' yet rendered the platform system
font. Bundle the canonical Geist family so it actually renders -- the typography
half of the mobile facelift (#2235).
- mobile/assets/fonts/: Geist Regular/Medium/SemiBold/Bold + Geist Mono (.ttf),
with SIL OFL-1.1 (OFL.txt).
- mobile/pubspec.yaml: declare the families under flutter > fonts (Geist
400/500/600/700; Geist Mono 400).
No code/layout changes -- every text surface inherits Geist via SureTheme.
Validated: flutter analyze --no-fatal-infos clean, flutter test 95 pass,
iOS + Android builds include Geist in the font manifest; real iOS-sim
before/after x light/dark screenshots confirm system font -> Geist.
