feat(library): pause and resume library scans

The scan progress tile offers Pause and Resume. A paused scan releases its foreground service and wake lock, shows a paused notice, and resumes from the next unscanned file.

lib/services/notification_service.dart

@@ -539,6 +539,25 @@ class NotificationService {
     );
   }
 
+  Future<void> showLibraryScanPaused({required int scannedFiles}) async {
+    if (!_isInitialized) await initialize();
+
+    await _showSafely(
+      id: libraryScanId,
+      title: _l10n?.notifLibraryScanPaused ?? 'Library scan paused',
+      body:
+          _l10n?.notifLibraryScanPausedBody(scannedFiles) ??
+          '$scannedFiles files scanned. Resume in Local Library settings to '
+              'continue from here.',
+      details: _details(library: true),
+    );
+  }
+
+  /// Clears a paused-scan notice once the foreground service shows progress.
+  Future<void> cancelLibraryScanNotification() async {
+    await _notifications.cancel(id: libraryScanId);
+  }
+
   Future<void> showUpdateDownloadProgress({
     required String version,
     required int received,

lib/services/platform_bridge.dart

@@ -2346,6 +2346,15 @@ class PlatformBridge {
     await _channel.invokeMethod('cancelLibraryScan');
   }
 
+  /// Holds the running native scan at its next file; it keeps its position.
+  static Future<void> pauseLibraryScan() async {
+    await _channel.invokeMethod('pauseLibraryScan');
+  }
+
+  static Future<void> resumeLibraryScan() async {
+    await _channel.invokeMethod('resumeLibraryScan');
+  }
+
   static Object? _decodeJsonResult(dynamic result) {
     if (result is String) {
       if (result.isEmpty) return null;