Frosted bottom bar: adjustable blur and opacity with Less/Default/More presets

Settings > Appearance shows a preset control plus Blur and Opacity sliders
(new NooSlider) while frosted glass is on; values persist and feed
NooBottomBar.frostedBlur/frostedOpacity. Default matches the old fixed look.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

lib/providers/settings_controller.dart

@@ -21,6 +21,30 @@ enum FabStyle { auto, mini, expanded }
 /// animated wave with a tick-mark thumb ([squiggly]).
 enum MediaProgressBarStyle { classic, wavy, slim, squiggly }
 
+/// The frosted-glass bottom bar's blur sigma and surface opacity, in three
+/// ready-made strengths (Settings, Appearance). Moving either slider off all
+/// three leaves no preset selected (a custom mix).
+enum FrostedGlassPreset {
+  less(blur: 10, opacity: 0.88, label: 'Less'),
+  standard(blur: 20, opacity: 0.72, label: 'Default'),
+  more(blur: 32, opacity: 0.55, label: 'More');
+
+  final double blur;
+  final double opacity;
+  final String label;
+
+  const FrostedGlassPreset({
+    required this.blur,
+    required this.opacity,
+    required this.label,
+  });
+}
+
+const double minFrostedBlur = 0;
+const double maxFrostedBlur = 40;
+const double minFrostedOpacity = 0.3;
+const double maxFrostedOpacity = 1.0;
+
 /// Global (not per-account) UI settings: theme, bottom-nav appearance, tab
 /// configuration, swipe actions. Independent of login state - these mean
 /// the same thing whether any account is signed in or not, unlike
@@ -39,6 +63,8 @@ class SettingsController extends ChangeNotifier {
   static const _prefFabStyle = 'ui_fab_style';
   static const _prefBottomBarStyle = 'ui_bottom_bar_style';
   static const _prefBottomBarFrosted = 'ui_bottom_bar_frosted';
+  static const _prefFrostedBlur = 'ui_bottom_bar_frosted_blur';
+  static const _prefFrostedOpacity = 'ui_bottom_bar_frosted_opacity';
   static const _prefNavMenuStyle = 'ui_nav_menu_style';
   static const _prefSearchInBottomBar = 'ui_search_in_bottom_bar';
   static const _prefAmoledDark = 'ui_amoled_dark';
@@ -53,6 +79,8 @@ class SettingsController extends ChangeNotifier {
   NooBottomBarStyle _bottomBarStyle = NooBottomBarStyle.attached;
   NooNavMenuStyle _navMenuStyle = NooNavMenuStyle.drawer;
   bool _bottomBarFrosted = false;
+  double _frostedBlur = FrostedGlassPreset.standard.blur;
+  double _frostedOpacity = FrostedGlassPreset.standard.opacity;
   bool _searchInBottomBar = false;
   bool _useDynamicColor = true;
   bool _amoledDark = false;
@@ -98,6 +126,14 @@ class SettingsController extends ChangeNotifier {
   ThemeMode get themeMode => _themeMode;
   NooBottomBarStyle get bottomBarStyle => _bottomBarStyle;
   bool get bottomBarFrosted => _bottomBarFrosted;
+  double get bottomBarFrostedBlur => _frostedBlur;
+  double get bottomBarFrostedOpacity => _frostedOpacity;
+
+  /// The preset the current blur/opacity match exactly, or null when the
+  /// sliders have been moved to something custom.
+  FrostedGlassPreset? get frostedPreset => FrostedGlassPreset.values
+      .where((p) => p.blur == _frostedBlur && p.opacity == _frostedOpacity)
+      .firstOrNull;
   NooNavMenuStyle get navMenuStyle => _navMenuStyle;
   bool get searchInBottomBar => _searchInBottomBar;
   bool get useDynamicColor => _useDynamicColor;
@@ -160,6 +196,15 @@ class SettingsController extends ChangeNotifier {
       }
       _bottomBarFrosted =
           prefs.getBool(_prefBottomBarFrosted) ?? _bottomBarFrosted;
+      _frostedBlur = (prefs.getDouble(_prefFrostedBlur) ?? _frostedBlur).clamp(
+        minFrostedBlur,
+        maxFrostedBlur,
+      );
+      _frostedOpacity =
+          (prefs.getDouble(_prefFrostedOpacity) ?? _frostedOpacity).clamp(
+            minFrostedOpacity,
+            maxFrostedOpacity,
+          );
       _searchInBottomBar =
           prefs.getBool(_prefSearchInBottomBar) ?? _searchInBottomBar;
       _useDynamicColor =
@@ -318,6 +363,27 @@ class SettingsController extends ChangeNotifier {
     _prefsFuture.then((p) => p.setString(_prefBottomBarStyle, style.name));
   }
 
+  void setFrostedBlur(double value) {
+    final v = value.clamp(minFrostedBlur, maxFrostedBlur);
+    if (_frostedBlur == v) return;
+    _frostedBlur = v;
+    notifyListeners();
+    _prefsFuture.then((p) => p.setDouble(_prefFrostedBlur, v));
+  }
+
+  void setFrostedOpacity(double value) {
+    final v = value.clamp(minFrostedOpacity, maxFrostedOpacity);
+    if (_frostedOpacity == v) return;
+    _frostedOpacity = v;
+    notifyListeners();
+    _prefsFuture.then((p) => p.setDouble(_prefFrostedOpacity, v));
+  }
+
+  void setFrostedPreset(FrostedGlassPreset preset) {
+    setFrostedBlur(preset.blur);
+    setFrostedOpacity(preset.opacity);
+  }
+
   void setBottomBarFrosted(bool value) {
     if (_bottomBarFrosted == value) return;
     _bottomBarFrosted = value;