Add setting for thumbnails quality

Shared/Defaults.swift

@@ -51,6 +51,7 @@ extension Defaults.Keys {
     static let channelOnThumbnail = Key<Bool>("channelOnThumbnail", default: true)
     static let timeOnThumbnail = Key<Bool>("timeOnThumbnail", default: true)
     static let roundedThumbnails = Key<Bool>("roundedThumbnails", default: true)
+    static let thumbnailsQuality = Key<ThumbnailsQuality>("thumbnailsQuality", default: .highest)
 
     static let activeBackend = Key<PlayerBackendType>("activeBackend", default: .mpv)
     static let quality = Key<ResolutionSetting>("quality", default: .best)
@@ -218,3 +219,7 @@ enum PlayerDetailsPageButtonLabelStyle: String, CaseIterable, Defaults.Serializa
         self == .iconAndText
     }
 }
+
+enum ThumbnailsQuality: String, CaseIterable, Defaults.Serializable {
+    case highest, medium, low
+}

Shared/Settings/BrowsingSettings.swift

@@ -9,6 +9,7 @@ struct BrowsingSettings: View {
     #if os(iOS)
         @Default(.lockPortraitWhenBrowsing) private var lockPortraitWhenBrowsing
     #endif
+    @Default(.thumbnailsQuality) private var thumbnailsQuality
     @Default(.channelOnThumbnail) private var channelOnThumbnail
     @Default(.timeOnThumbnail) private var timeOnThumbnail
     @Default(.visibleSections) private var visibleSections
@@ -65,6 +66,7 @@ struct BrowsingSettings: View {
 
     private var thumbnailsSettings: some View {
         Section(header: SettingsHeader(text: "Thumbnails")) {
+            thumbnailsQualityPicker
             #if !os(tvOS)
                 Toggle("Round corners", isOn: $roundedThumbnails)
             #endif
@@ -73,6 +75,21 @@ struct BrowsingSettings: View {
         }
     }
 
+    private var thumbnailsQualityPicker: some View {
+        Picker("Quality", selection: $thumbnailsQuality) {
+            ForEach(ThumbnailsQuality.allCases, id: \.self) { quality in
+                Text(quality.rawValue.capitalized + " quality").tag(quality)
+            }
+        }
+        .labelsHidden()
+
+        #if os(iOS)
+            .pickerStyle(.automatic)
+        #elseif os(tvOS)
+            .pickerStyle(.inline)
+        #endif
+    }
+
     private var visibleSectionsSettings: some View {
         Section(header: SettingsHeader(text: "Sections")) {
             #if os(macOS)