Use CSS keyframe animation for spinner on web (#3411)

* Use css keyframe animation for spinner on web

* duplicate css to index.html

src/components/Loader.tsx

@@ -1,13 +1,13 @@
 import React from 'react'
 import Animated, {
   Easing,
-  useSharedValue,
   useAnimatedStyle,
+  useSharedValue,
   withRepeat,
   withTiming,
 } from 'react-native-reanimated'
 
-import {atoms as a, useTheme, flatten} from '#/alf'
+import {atoms as a, flatten, useTheme} from '#/alf'
 import {Props, useCommonSVGProps} from '#/components/icons/common'
 import {Loader_Stroke2_Corner0_Rounded as Icon} from '#/components/icons/Loader'
 

src/components/Loader.web.tsx

@@ -0,0 +1,34 @@
+import React from 'react'
+import {View} from 'react-native'
+
+import {atoms as a, flatten, useTheme} from '#/alf'
+import {Props, useCommonSVGProps} from '#/components/icons/common'
+import {Loader_Stroke2_Corner0_Rounded as Icon} from '#/components/icons/Loader'
+
+export function Loader(props: Props) {
+  const t = useTheme()
+  const common = useCommonSVGProps(props)
+
+  return (
+    <View
+      style={[
+        a.relative,
+        a.justify_center,
+        a.align_center,
+        {width: common.size, height: common.size},
+      ]}>
+      {/* css rotation animation - /bskyweb/templates/base.html */}
+      <div className="rotate-500ms">
+        <Icon
+          {...props}
+          style={[
+            a.absolute,
+            a.inset_0,
+            t.atoms.text_contrast_high,
+            flatten(props.style),
+          ]}
+        />
+      </div>
+    </View>
+  )
+}