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>

test/widgets/noo/core_test.dart

@@ -10,6 +10,7 @@ import 'package:noo/widgets/noo/core/noo_chip.dart';
 import 'package:noo/widgets/noo/core/noo_fab.dart';
 import 'package:noo/widgets/noo/core/noo_progress_bar.dart';
 import 'package:noo/widgets/noo/core/noo_search_field.dart';
+import 'package:noo/widgets/noo/core/noo_slider.dart';
 import 'package:noo/widgets/noo/core/noo_segmented_control.dart';
 import 'package:noo/widgets/noo/core/noo_toggle.dart';
 import 'package:noo/widgets/noo/nav/noo_nav_style.dart';
@@ -98,6 +99,35 @@ void main() {
     }
   });
 
+  group('NooSlider', () {
+    testNooWidgets('dragging reports a value within min..max', (
+      tester,
+      theme,
+      c,
+    ) async {
+      var value = 10.0;
+      await pumpNoo(
+        tester,
+        StatefulBuilder(
+          builder: (context, setState) => SizedBox(
+            width: 300,
+            child: NooSlider(
+              value: value,
+              min: 0,
+              max: 40,
+              onChanged: (v) => setState(() => value = v),
+            ),
+          ),
+        ),
+        theme: theme,
+      );
+      await tester.drag(find.byType(Slider), const Offset(150, 0));
+      await tester.pump();
+      expect(value, greaterThan(10));
+      expect(value, lessThanOrEqualTo(40));
+    });
+  });
+
   group('NooAvatar', () {
     testNooWidgets('current user uses accent-soft/accent-text', (
       tester,

test/widgets/noo/nav_test.dart

@@ -1,3 +1,4 @@
+import 'dart:ui' show ImageFilter;
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:lucide_icons_flutter/lucide_icons.dart';
@@ -62,6 +63,44 @@ void main() {
       }
     }
 
+    testNooWidgets('frosted bar uses the given blur sigma and fill opacity', (
+      tester,
+      theme,
+      c,
+    ) async {
+      await pumpNoo(
+        tester,
+        SizedBox(
+          width: 360,
+          height: 120,
+          child: NooBottomBar(
+            style: NooNavStyle.android,
+            frosted: true,
+            frostedBlur: 31,
+            frostedOpacity: 0.5,
+            destinations: _destinations,
+            selectedIndex: 0,
+            onSelected: (_) {},
+          ),
+        ),
+        theme: theme,
+      );
+      expect(
+        tester.widget<BackdropFilter>(find.byType(BackdropFilter)).filter,
+        ImageFilter.blur(sigmaX: 31, sigmaY: 31),
+      );
+      expect(
+        find.byWidgetPredicate(
+          (w) =>
+              w is Container &&
+              w.decoration is BoxDecoration &&
+              (w.decoration as BoxDecoration).color ==
+                  c.surface.withValues(alpha: 0.5),
+        ),
+        findsOneWidget,
+      );
+    });
+
     test('drawsBehindBody: floating or frosted', () {
       expect(
         NooBottomBar.drawsBehindBody(NooBottomBarStyle.attached, false),