* feat(mobile): add SureSpacing + SureTypography scale tokens
Introduce hand-authored spacing and type-scale constants mirroring the
Tailwind defaults the web design system relies on, so widgets reference a
named step instead of a raw numeric EdgeInsets/SizedBox/fontSize.
- SureSpacing: xs..huge mapping to Tailwind space-1..space-8 (4..32px).
- SureTypography: xs..xxl mapping to Tailwind text-xs..text-2xl font sizes.
Both are hand-written rather than generated from sure.tokens.json because
spacing and the type ramp come from Tailwind's built-in scale, not the
canonical token file (consistent with the tracker's guidance).
Adopt them in the existing primitives (card padding, button metrics +
gap, chip/segmented/list-group gaps and padding, text-field padding +
label gap). All migrations are value-preserving — each token equals the
literal it replaces — so there is no layout change; off-scale one-offs
(control heights, hairlines, deliberate 14px field padding) stay literal.
flutter analyze: no new issues; full suite (166) green.
* docs(mobile): note off-scale SureChip inset; expose SureTypography line heights
Address review feedback (jjmata):
- SureChip: add an inline comment explaining the horizontal:14 content inset is
deliberately off the SureSpacing scale (between lg=12 and xl=16) — a tuned
FilterChip-parity dimension, not a spacing step — so it isn't "fixed" to a
token later.
- SureTypography: expose the paired line heights (xsLineHeight … xxlLineHeight,
logical px matching the Tailwind text-* defaults) that were previously only in
doc comments, with a note on deriving Flutter's TextStyle.height multiplier
(lineHeight / fontSize). No behavior change.
Introduce a custom (non-Material) SureButton mirroring the web DS::Button: variants (primary, secondary, destructive, outline, ghost), sizes (sm/md/lg ≈ 28/36/48), optional leading widget, fullWidth, loading, and disabled. Colors resolve from the SureColors palette and the shape from radius tokens (radiusMd/radiusLg); flat custom press feedback (no Material ripple). Dimensions mirror the web DS::Buttonish::SIZES (the web composes these from Tailwind's standard scale rather than brand tokens, so they're not in sure.tokens.json).
Migrate the three main-view login buttons onto it — Sign In (primary, lg, loading), Sign in with Google (outline + SVG leading), and API-Key Login (ghost). The two buttons inside the API-key modal dialog are left for a follow-up.
Part of #2235.
