feat(player): add beat-matched AutoMix and refine Mornye navigation

Add default-off local beat analysis, pitch-preserving tempo matching, crossfade fallback, and cancellation-safe two-deck playback. Expose AutoMix in settings and the Mornye queue.

Separate Search from Home, remove the Mornye greeting, and keep Home/Search icons moving continuously between full and compact navigation. Restore expansion on upward Library scrolling.

Validate beat analysis, transport handoff and cancellation, settings persistence, and navigation behavior. Flutter analysis and the signed iOS simulator build pass.

test/shell_navigation_service_test.dart

@@ -5,67 +5,95 @@ import 'package:spotiflac_android/services/shell_navigation_service.dart';
 import 'package:spotiflac_android/widgets/view_queue_snackbar_action.dart';
 
 void main() {
-  testWidgets('first search request reaches a lazily mounted Home tab', (
-    tester,
-  ) async {
-    await tester.pumpWidget(const MaterialApp(home: _SearchShell()));
-    await tester.pumpAndSettle();
-    expect(find.byType(TextField), findsNothing);
+  for (final (separateSearch, showRepo) in [
+    (false, false),
+    (true, false),
+    (true, true),
+  ]) {
+    testWidgets(
+      'first search request reaches the lazy page (separate=$separateSearch, repo=$showRepo)',
+      (tester) async {
+        await tester.pumpWidget(
+          MaterialApp(
+            home: _SearchShell(
+              separateSearch: separateSearch,
+              showRepo: showRepo,
+            ),
+          ),
+        );
+        await tester.pumpAndSettle();
+        expect(find.byType(TextField), findsNothing);
 
-    await tester.tap(find.text('Search'));
-    await tester.pumpAndSettle();
-    final field = tester.widget<TextField>(find.byType(TextField));
-    expect(field.focusNode!.hasFocus, isTrue);
-    expect(tester.testTextInput.isVisible, isTrue);
-  });
-
-  testWidgets('one search request returns from an album and focuses Home', (
-    tester,
-  ) async {
-    await tester.pumpWidget(const MaterialApp(home: _SearchShell()));
-    await tester.tap(find.text('Search'));
-    await tester.pumpAndSettle();
-    final navigator = ShellNavigationService.homeTabNavigatorKey.currentState!;
-    navigator.push(
-      MaterialPageRoute<void>(
-        builder: (_) => const Scaffold(body: Text('Album')),
-      ),
+        await tester.tap(find.text('Search'));
+        await tester.pumpAndSettle();
+        final field = tester.widget<TextField>(find.byType(TextField));
+        expect(field.focusNode!.hasFocus, isTrue);
+        expect(tester.testTextInput.isVisible, isTrue);
+      },
     );
-    await tester.pumpAndSettle();
-    await tester.tap(find.text('Search'));
-    await tester.pumpAndSettle();
-    expect(find.text('Album'), findsNothing);
-    final field = tester.widget<TextField>(find.byType(TextField));
-    expect(field.focusNode!.hasFocus, isTrue);
-    expect(tester.testTextInput.isVisible, isTrue);
-  });
+
+    testWidgets(
+      'search returns from an album to its own tab (separate=$separateSearch, repo=$showRepo)',
+      (tester) async {
+        await tester.pumpWidget(
+          MaterialApp(
+            home: _SearchShell(
+              separateSearch: separateSearch,
+              showRepo: showRepo,
+            ),
+          ),
+        );
+        await tester.tap(find.text('Search'));
+        await tester.pumpAndSettle();
+        final navigator =
+            (separateSearch
+                    ? ShellNavigationService.searchTabNavigatorKey
+                    : ShellNavigationService.homeTabNavigatorKey)
+                .currentState!;
+        expect(ShellNavigationService.activeTabNavigator(), same(navigator));
+        navigator.push(
+          MaterialPageRoute<void>(
+            builder: (_) => const Scaffold(body: Text('Album')),
+          ),
+        );
+        await tester.pumpAndSettle();
+        await tester.tap(find.text('Search'));
+        await tester.pumpAndSettle();
+        expect(find.text('Album'), findsNothing);
+        final field = tester.widget<TextField>(find.byType(TextField));
+        expect(field.focusNode!.hasFocus, isTrue);
+        expect(tester.testTextInput.isVisible, isTrue);
+      },
+    );
+  }
 
   testWidgets(
-    'search selects Home before requesting focus and stops when shell is absent',
+    'search selects its tab before requesting focus and stops when shell is absent',
     (tester) async {
       final owner = Object();
-      var selectedHome = false;
+      ShellNavigationService.syncState(currentTabIndex: 0, showRepoTab: false);
+      var selectedSearch = false;
       var focusRequests = 0;
       void onSearch() {
-        expect(selectedHome, isTrue);
+        expect(selectedSearch, isTrue);
         focusRequests++;
       }
 
-      ShellNavigationService.homeSearchRequests.addListener(onSearch);
+      ShellNavigationService.searchRequests.addListener(onSearch);
       addTearDown(() {
-        ShellNavigationService.homeSearchRequests.removeListener(onSearch);
+        ShellNavigationService.searchRequests.removeListener(onSearch);
         ShellNavigationService.unregisterTabSelectionHandler(owner);
       });
       ShellNavigationService.registerTabSelectionHandler(
         owner: owner,
-        handler: (tab) => selectedHome = tab == ShellTab.home,
+        handler: (tab) => selectedSearch = tab == ShellTab.search,
       );
-      ShellNavigationService.requestHomeSearch();
+      ShellNavigationService.requestSearch();
       expect(focusRequests, 0);
       await tester.pump();
       expect(focusRequests, 1);
       ShellNavigationService.unregisterTabSelectionHandler(owner);
-      ShellNavigationService.requestHomeSearch();
+      ShellNavigationService.requestSearch();
       expect(focusRequests, 1);
     },
   );
@@ -155,7 +183,10 @@ void main() {
 }
 
 class _SearchShell extends StatefulWidget {
-  const _SearchShell();
+  const _SearchShell({required this.separateSearch, required this.showRepo});
+
+  final bool separateSearch;
+  final bool showRepo;
 
   @override
   State<_SearchShell> createState() => _SearchShellState();
@@ -163,22 +194,29 @@ class _SearchShell extends StatefulWidget {
 
 class _SearchShellState extends State<_SearchShell> {
   final _pages = PageController(initialPage: 1);
-  late final _observer = ShellChromeObserver(
-    ShellNavigationService.homeTabNavigatorKey,
-  );
+  GlobalKey<NavigatorState> get _navigatorKey => widget.separateSearch
+      ? ShellNavigationService.searchTabNavigatorKey
+      : ShellNavigationService.homeTabNavigatorKey;
+  int get _searchIndex => widget.separateSearch ? (widget.showRepo ? 4 : 3) : 0;
+  late final _observer = ShellChromeObserver(_navigatorKey);
 
   @override
   void initState() {
     super.initState();
-    ShellNavigationService.syncState(currentTabIndex: 1, showRepoTab: false);
+    ShellNavigationService.syncState(
+      currentTabIndex: 1,
+      showRepoTab: widget.showRepo,
+      showSearchTab: widget.separateSearch,
+    );
     ShellNavigationService.registerTabSelectionHandler(
       owner: this,
       handler: (_) {
         ShellNavigationService.syncState(
-          currentTabIndex: 0,
-          showRepoTab: false,
+          currentTabIndex: _searchIndex,
+          showRepoTab: widget.showRepo,
+          showSearchTab: widget.separateSearch,
         );
-        _pages.jumpToPage(0);
+        _pages.jumpToPage(_searchIndex);
       },
     );
   }
@@ -196,17 +234,17 @@ class _SearchShellState extends State<_SearchShell> {
     body: Column(
       children: [
         TextButton(
-          onPressed: ShellNavigationService.requestHomeSearch,
+          onPressed: ShellNavigationService.requestSearch,
           child: const Text('Search'),
         ),
         Expanded(
           child: PageView.builder(
             controller: _pages,
-            itemCount: 2,
-            itemBuilder: (_, index) => index == 1
+            itemCount: widget.separateSearch ? _searchIndex + 1 : 2,
+            itemBuilder: (_, index) => index != _searchIndex
                 ? const Text('Library')
                 : Navigator(
-                    key: ShellNavigationService.homeTabNavigatorKey,
+                    key: _navigatorKey,
                     observers: [_observer],
                     onGenerateRoute: (_) => MaterialPageRoute<void>(
                       builder: (_) => const _SearchHome(),
@@ -232,7 +270,7 @@ class _SearchHomeState extends State<_SearchHome> {
   @override
   void initState() {
     super.initState();
-    ShellNavigationService.homeSearchRequests.addListener(_onSearch);
+    ShellNavigationService.searchRequests.addListener(_onSearch);
   }
 
   void _onSearch() {
@@ -243,7 +281,7 @@ class _SearchHomeState extends State<_SearchHome> {
 
   @override
   void dispose() {
-    ShellNavigationService.homeSearchRequests.removeListener(_onSearch);
+    ShellNavigationService.searchRequests.removeListener(_onSearch);
     _focus.dispose();
     super.dispose();
   }