Allow admins to configure instance favicon and logo (#30040)

app/models/form/admin_settings.rb

@@ -37,6 +37,8 @@ class Form::AdminSettings
     status_page_url
     captcha_enabled
     authorized_fetch
+    app_icon
+    favicon
   ).freeze
 
   INTEGER_KEYS = %i(
@@ -63,6 +65,8 @@ class Form::AdminSettings
   UPLOAD_KEYS = %i(
     thumbnail
     mascot
+    app_icon
+    favicon
   ).freeze
 
   OVERRIDEN_SETTINGS = {

app/models/site_upload.rb

@@ -19,7 +19,15 @@
 class SiteUpload < ApplicationRecord
   include Attachmentable
 
+  FAVICON_SIZES = [16, 32, 48].freeze
+  APPLE_ICON_SIZES   = [57, 60, 72, 76, 114, 120, 144, 152, 167, 180, 1024].freeze
+  ANDROID_ICON_SIZES = [36, 48, 72, 96, 144, 192, 256, 384, 512].freeze
+
+  APP_ICON_SIZES = (APPLE_ICON_SIZES + ANDROID_ICON_SIZES).uniq.freeze
+
   STYLES = {
+    app_icon: APP_ICON_SIZES.each_with_object({}) { |size, hash| hash[size.to_s.to_sym] = "#{size}x#{size}#" }.freeze,
+    favicon: FAVICON_SIZES.each_with_object({}) { |size, hash| hash[size.to_s.to_sym] = "#{size}x#{size}#" }.freeze,
     thumbnail: {
       '@1x': {
         format: 'png',