perf(store): skip invisible backdrop blur on repo cards

Repo cards, category chips and the Store search field scroll over the plain page background, where a backdrop blur changes nothing visible but re-filters each panel on every scroll frame. MornyeGlass.navigation gains samplesBackdrop; these panels keep the same tint, rim, shadow and glass clarity without the blur pass. Floating chrome keeps its blur.

lib/screens/repo_tab.dart

@@ -128,6 +128,7 @@ class _RepoTabState extends ConsumerState<RepoTab> {
                     controller: _searchController,
                     hintText: context.l10n.storeSearch,
                     clearTooltip: context.l10n.dialogClear,
+                    samplesBackdrop: false,
                     onChanged: (value) =>
                         ref.read(repoProvider.notifier).setSearchQuery(value),
                     onClear: () =>
@@ -657,9 +658,11 @@ class _CategoryChip extends ConsumerWidget {
         label: label,
         onTap: onTap,
         excludeSemantics: true,
+        // Scrolls with the list over the plain page: see ExtensionRepoCard.
         child: MornyeGlass.navigation(
           radius: 24,
           blurEnabled: ref.watch(mornyeBlurEnabledProvider),
+          samplesBackdrop: false,
           child: Material(
             color: Colors.transparent,
             child: InkWell(

lib/widgets/app_search_field.dart

@@ -24,6 +24,7 @@ class AppSearchField extends StatelessWidget {
     this.suffixIcon,
     this.focusNode,
     this.autofocus = false,
+    this.samplesBackdrop = true,
   });
 
   final TextEditingController controller;
@@ -37,6 +38,10 @@ class AppSearchField extends StatelessWidget {
   final FocusNode? focusNode;
   final bool autofocus;
 
+  /// See [MornyeGlass.samplesBackdrop]: false where the field scrolls over
+  /// the plain page background.
+  final bool samplesBackdrop;
+
   @override
   Widget build(BuildContext context) {
     final colorScheme = Theme.of(context).colorScheme;
@@ -107,6 +112,7 @@ class AppSearchField extends StatelessWidget {
       builder: (context, ref, child) => MornyeGlass.navigation(
         radius: 28,
         blurEnabled: ref.watch(mornyeBlurEnabledProvider),
+        samplesBackdrop: samplesBackdrop,
         child: child!,
       ),
       child: field,

lib/widgets/extension_repo_card.dart

@@ -34,9 +34,12 @@ class ExtensionRepoCard extends ConsumerWidget {
     }
     return Padding(
       padding: margin,
+      // Repo pages scroll these cards over the plain page background, where a
+      // backdrop blur is invisible but re-filters the whole card every frame.
       child: MornyeGlass.navigation(
         radius: 24,
         blurEnabled: ref.watch(mornyeBlurEnabledProvider),
+        samplesBackdrop: false,
         child: Material(color: Colors.transparent, child: child),
       ),
     );

lib/widgets/mornye_chrome.dart

@@ -257,7 +257,8 @@ class MornyeGlass extends StatelessWidget {
     this.backdropFilter,
   }) : _useLens = true,
        firstInGroup = true,
-       lastInGroup = true;
+       lastInGroup = true,
+       samplesBackdrop = true;
 
   /// Shares the navigation bar's tint, blur and subtle edge reflections.
   const MornyeGlass.navigation({
@@ -271,10 +272,17 @@ class MornyeGlass extends StatelessWidget {
     this.tintOpacity,
     this.tintColor,
     this.backdropFilter,
+    this.samplesBackdrop = true,
   }) : _useLens = false;
 
   final Widget child;
   final bool blurEnabled;
+
+  /// False for panels that only ever scroll over the plain page background.
+  /// Blurring a uniform backdrop changes nothing visible but re-filters the
+  /// panel's whole area on every scroll frame; the translucent tint, rim and
+  /// clarity preference stay exactly as with sampling.
+  final bool samplesBackdrop;
   final double radius;
   final bool _useLens;
   final bool firstInGroup;
@@ -311,6 +319,7 @@ class MornyeGlass extends StatelessWidget {
       tintOpacity: tintOpacity,
       tintColor: tintColor,
       backdropFilter: backdropFilter,
+      samplesBackdrop: samplesBackdrop,
       child: useGlass ? lens(child) : child,
     );
   }
@@ -389,6 +398,7 @@ class _MornyeGlassSurface extends StatelessWidget {
     this.tintOpacity,
     this.tintColor,
     this.backdropFilter,
+    this.samplesBackdrop = true,
   });
 
   final Widget child;
@@ -400,6 +410,7 @@ class _MornyeGlassSurface extends StatelessWidget {
   final double? tintOpacity;
   final Color? tintColor;
   final ImageFilter? backdropFilter;
+  final bool samplesBackdrop;
 
   @override
   Widget build(BuildContext context) {
@@ -452,7 +463,7 @@ class _MornyeGlassSurface extends StatelessWidget {
         ),
         child: ClipRRect(
           borderRadius: shape,
-          child: useBlur
+          child: useBlur && samplesBackdrop
               ? BackdropFilter(
                   filter:
                       backdropFilter ?? (dark ? _darkBackdrop : _backdropBlur),

test/mornye_glass_level_test.dart

@@ -5,6 +5,7 @@ import 'package:liquid_glass_easy/liquid_glass_easy.dart';
 import 'package:spotiflac_android/providers/runtime_profile_provider.dart';
 import 'package:spotiflac_android/theme/mornye_theme.dart';
 import 'package:spotiflac_android/widgets/app_switch.dart';
+import 'package:spotiflac_android/widgets/extension_repo_card.dart';
 import 'package:spotiflac_android/widgets/mornye_chrome.dart';
 
 MornyeGlassLevel _levelFor({
@@ -183,6 +184,70 @@ void main() {
     });
   }
 
+  testWidgets('plain-page panels keep the glass tint without a backdrop pass', (
+    tester,
+  ) async {
+    Color? tintOf(Finder panel) {
+      final decorated = tester
+          .widgetList<DecoratedBox>(
+            find.descendant(of: panel, matching: find.byType(DecoratedBox)),
+          )
+          .map((box) => box.decoration)
+          .whereType<BoxDecoration>()
+          .firstWhere((decoration) => decoration.color != null);
+      return decorated.color;
+    }
+
+    await tester.pumpWidget(
+      ProviderScope(
+        child: MaterialApp(
+          theme: MornyeTheme.build(Brightness.dark),
+          home: const Scaffold(
+            body: Column(
+              children: [
+                MornyeGlass.navigation(
+                  key: ValueKey('sampled'),
+                  blurEnabled: true,
+                  child: SizedBox(width: 200, height: 40),
+                ),
+                MornyeGlass.navigation(
+                  key: ValueKey('plain-page'),
+                  blurEnabled: true,
+                  samplesBackdrop: false,
+                  child: SizedBox(width: 200, height: 40),
+                ),
+                ExtensionRepoCard(child: SizedBox(width: 200, height: 40)),
+              ],
+            ),
+          ),
+        ),
+      ),
+    );
+    await tester.pump();
+
+    final sampled = find.byKey(const ValueKey('sampled'));
+    final plain = find.byKey(const ValueKey('plain-page'));
+    expect(
+      find.descendant(of: sampled, matching: find.byType(BackdropFilter)),
+      findsOneWidget,
+    );
+    expect(
+      find.descendant(of: plain, matching: find.byType(BackdropFilter)),
+      findsNothing,
+    );
+    expect(
+      find.descendant(
+        of: find.byType(ExtensionRepoCard),
+        matching: find.byType(BackdropFilter),
+      ),
+      findsNothing,
+    );
+    // Same translucent material, so the page looks identical behind it.
+    expect(tintOf(plain), tintOf(sampled));
+    expect(tintOf(plain)!.a, lessThan(1));
+    expect(tester.takeException(), isNull);
+  });
+
   testWidgets('liquid level keeps the shader glass', (tester) async {
     await tester.pumpWidget(
       ProviderScope(