fix: resolve all remaining lint issues for CI

- Remove unused _androidAppId field from launch_review_service
- Replace deprecated withOpacity() with withValues(alpha:)
- Ignore parameter_assignments lint in ffmpeg_kit_service (intentional design)

Author: it5prasoon

lib/src/core/services/ffmpeg_kit_service/ffmpeg_kit_service.dart

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a GPL-style license that can be found
 // in the LICENSE file.
 
-// ignore_for_file: lines_longer_than_80_chars
+// ignore_for_file: lines_longer_than_80_chars, parameter_assignments
 
 import 'dart:async';
 import 'dart:developer';

lib/src/core/services/launch_review_service/launch_review_service.dart

@@ -19,10 +19,8 @@ class LaunchReviewService {
   const LaunchReviewService({
     String? androidAppId,
     String? iOSAppId,
-  })  : _androidAppId = androidAppId,
-        _iOSAppId = iOSAppId;
+  }) : _iOSAppId = iOSAppId;
 
-  final String? _androidAppId;
   final String? _iOSAppId;
 
   /// Launches the app store page for this app.

lib/src/presentation/more/view/widgets/copyright_widget.dart

@@ -39,7 +39,7 @@ class _CopyrightWidget extends StatelessWidget {
             'Based on VSound by BBK Development',
             style: context.textTheme.bodySmall?.copyWith(
               fontSize: 10,
-              color: context.textTheme.bodySmall?.color?.withOpacity(0.7),
+              color: context.textTheme.bodySmall?.color?.withValues(alpha: 0.7),
             ),
             textAlign: TextAlign.center,
           ),
@@ -48,7 +48,7 @@ class _CopyrightWidget extends StatelessWidget {
             'Open Source (GPL v3) • github.com/CodeShipping/AV-Editor',
             style: context.textTheme.bodySmall?.copyWith(
               fontSize: 10,
-              color: context.textTheme.bodySmall?.color?.withOpacity(0.7),
+              color: context.textTheme.bodySmall?.color?.withValues(alpha: 0.7),
             ),
             textAlign: TextAlign.center,
           ),