Design system tweaks (#2822)

* Tweak palette, theme naming, update usages

* Update Typography, replace the few usages

src/screens/Onboarding/StepModeration/AdultContentEnabledPref.tsx

@@ -96,7 +96,7 @@ export function AdultContentEnabledPref({
           <Text
             style={[
               a.flex_1,
-              t.atoms.text_contrast_700,
+              t.atoms.text_contrast_medium,
               a.leading_snug,
               {paddingTop: 1},
             ]}>

src/screens/Onboarding/StepModeration/ModerationOption.tsx

@@ -57,7 +57,7 @@ export function ModerationOption({
       entering={isMounted.current ? FadeIn : undefined}>
       <View style={[a.gap_xs, {width: '50%'}]}>
         <Text style={[a.font_bold]}>{groupInfo.title}</Text>
-        <Text style={[t.atoms.text_contrast_700, a.leading_snug]}>
+        <Text style={[t.atoms.text_contrast_medium, a.leading_snug]}>
           {groupInfo.subtitle}
         </Text>
       </View>