fix(ui): center modals on large screens, modernize edit-metadata + convert sheets, themed badges, fix artist skeleton and format-editor crash

- app: clear displayFeatures so bottom sheets/dialogs center on large/foldable screens

- edit metadata sheet: card sections, modern label-above inputs, elegant collapsible headers, removed title icon

- convert + batch convert: modern card-based sheets; shared BatchConvertSheet widget

- queue: keep selection toolbar hidden until modal close animation finishes

- 24-bit and In Library badges now use primary dynamic color

- artist skeleton: remove duplicate name/listeners lines, keep cover placeholder

- files settings: own filename-format controller in a StatefulWidget to fix use-after-dispose crash

lib/app.dart

@@ -114,6 +114,19 @@ class SpotiFLACApp extends ConsumerWidget {
           scrollBehavior: scrollBehavior,
           themeAnimationDuration: const Duration(milliseconds: 300),
           themeAnimationCurve: Curves.easeInOut,
+          // Treat the display as one continuous surface. Some large/foldable
+          // devices report a full-height display feature (hinge/cutout) which
+          // makes Flutter split modal routes into a sub-screen, leaving bottom
+          // sheets and dialogs visibly off-center instead of centered on the
+          // full screen. Clearing displayFeatures keeps them centered for every
+          // modal/dialog generically, without per-sheet workarounds.
+          builder: (context, child) {
+            final mediaQuery = MediaQuery.of(context);
+            return MediaQuery(
+              data: mediaQuery.copyWith(displayFeatures: const []),
+              child: child ?? const SizedBox.shrink(),
+            );
+          },
           routerConfig: router,
           locale: locale,
           localeResolutionCallback: (deviceLocale, supportedLocales) {