Brand tuning: switch from "blueprint B" to "cloud imagery" (#96)

* Switch app icon to bluesky image

* Update splash screen to clouds

* Update login screen to use branding

* Lighten the shadows in the brand imagery

src/view/lib/assets.native.ts

@@ -2,3 +2,4 @@ import {ImageSourcePropType} from 'react-native'
 
 export const DEF_AVATAR: ImageSourcePropType = require('../../../public/img/default-avatar.jpg')
 export const TABS_EXPLAINER: ImageSourcePropType = require('../../../public/img/tabs-explainer.jpg')
+export const CLOUD_SPLASH: ImageSourcePropType = require('../../../public/img/cloud-splash.png')

src/view/lib/assets.ts

@@ -4,3 +4,4 @@ export const DEF_AVATAR: ImageSourcePropType = {uri: '/img/default-avatar.jpg'}
 export const TABS_EXPLAINER: ImageSourcePropType = {
   uri: '/img/tabs-explainer.jpg',
 }
+export const CLOUD_SPLASH: ImageSourcePropType = {uri: '/img/cloud-splash.png'}