[APP-1310] Button cleanup (#8754)

* Rm gradient buttons from Storybook

* TEMP move storybook button section

* Remove gradient_sky

* Remove actual defs for gradient_sky and gradient_primary

* Remove other gradient defs

* Remove gradient support entirely

* Deprecate 'variant' in favor of 'color'

* Fork base styles codepath to make variant deprecation more obvious

* Remove text styles for when no color is set, never been used

* Fork text styles codepath to make variant deprecation more obvious

* Revert temp storybook commit, remove deprecated values

* Replace remaining gradient button usage

src/components/Lists.tsx

@@ -1,7 +1,8 @@
-import React, {memo} from 'react'
-import {StyleProp, View, ViewStyle} from 'react-native'
+import {memo} from 'react'
+import {type StyleProp, View, type ViewStyle} from 'react-native'
 import {msg, Trans} from '@lingui/macro'
 import {useLingui} from '@lingui/react'
+import type React from 'react'
 
 import {cleanError} from '#/lib/strings/errors'
 import {CenteredView} from '#/view/com/util/Views'
@@ -95,7 +96,7 @@ function ListFooterMaybeError({
           )}
         </Text>
         <Button
-          variant="gradient"
+          variant="solid"
           label={_(msg`Press to retry`)}
           style={[
             a.align_center,