feat: use custom FFmpeg AAR for Android, reduce APK size

- Replace ffmpeg_kit_flutter plugin with custom AAR (arm64 + arm7a only)
- Add MethodChannel bridge for FFmpeg in MainActivity
- Create separate pubspec_ios.yaml for iOS builds with ffmpeg_kit plugin
- Update GitHub workflow to swap pubspec for iOS builds
- Reduces Android APK size by ~50MB

lib/constants/app_info.dart

@@ -1,8 +1,8 @@
 /// App version and info constants
 /// Update version here only - all other files will reference this
 class AppInfo {
-  static const String version = '2.0.6';
-  static const String buildNumber = '36';
+  static const String version = '2.0.7-preview';
+  static const String buildNumber = '37';
   static const String fullVersion = '$version+$buildNumber';
   
   

lib/providers/download_queue_provider.dart

@@ -4,8 +4,6 @@ import 'dart:io';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:shared_preferences/shared_preferences.dart';
-import 'package:ffmpeg_kit_flutter_new_audio/ffmpeg_kit.dart';
-import 'package:ffmpeg_kit_flutter_new_audio/return_code.dart';
 import 'package:spotiflac_android/models/download_item.dart';
 import 'package:spotiflac_android/models/settings.dart';
 import 'package:spotiflac_android/models/track.dart';
@@ -745,25 +743,12 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
       // For now, we'll use FFmpeg to embed cover since Go backend expects to download the file
       // FFmpeg can embed cover art to FLAC
       if (coverPath != null && await File(coverPath).exists()) {
-        final tempOutput = '$flacPath.tmp';
-        final command = '-i "$flacPath" -i "$coverPath" -map 0:a -map 1:0 -c copy -metadata:s:v title="Album cover" -metadata:s:v comment="Cover (front)" -disposition:v attached_pic "$tempOutput" -y';
+        final result = await FFmpegService.embedCover(flacPath, coverPath);
         
-        final session = await FFmpegKit.execute(command);
-        final returnCode = await session.getReturnCode();
-        
-        if (ReturnCode.isSuccess(returnCode)) {
-          // Replace original with temp
-          await File(flacPath).delete();
-          await File(tempOutput).rename(flacPath);
+        if (result != null) {
           _log.d('Cover embedded via FFmpeg');
         } else {
-          // Try alternative method using metaflac-style embedding
-          _log.w('FFmpeg cover embed failed, trying alternative...');
-          // Clean up temp file if exists
-          final tempFile = File(tempOutput);
-          if (await tempFile.exists()) {
-            await tempFile.delete();
-          }
+          _log.w('FFmpeg cover embed failed');
         }
         
         // Clean up cover file

lib/services/ffmpeg_service.dart

@@ -1,12 +1,30 @@
 import 'dart:io';
-import 'package:ffmpeg_kit_flutter_new_audio/ffmpeg_kit.dart';
-import 'package:ffmpeg_kit_flutter_new_audio/return_code.dart';
+import 'package:flutter/services.dart';
 import 'package:spotiflac_android/utils/logger.dart';
 
 final _log = AppLogger('FFmpeg');
 
 /// FFmpeg service for audio conversion and remuxing
+/// Uses native MethodChannel to call FFmpegKit from local AAR
 class FFmpegService {
+  static const _channel = MethodChannel('com.zarz.spotiflac/ffmpeg');
+
+  /// Execute FFmpeg command and return result
+  static Future<FFmpegResult> _execute(String command) async {
+    try {
+      final result = await _channel.invokeMethod('execute', {'command': command});
+      final map = Map<String, dynamic>.from(result);
+      return FFmpegResult(
+        success: map['success'] as bool,
+        returnCode: map['returnCode'] as int,
+        output: map['output'] as String,
+      );
+    } catch (e) {
+      _log.e('FFmpeg execute error: $e');
+      return FFmpegResult(success: false, returnCode: -1, output: e.toString());
+    }
+  }
+
   /// Convert M4A (DASH segments) to FLAC
   /// Returns the output file path on success, null on failure
   static Future<String?> convertM4aToFlac(String inputPath) async {
@@ -16,10 +34,9 @@ class FFmpegService {
     final command =
         '-i "$inputPath" -c:a flac -compression_level 8 "$outputPath" -y';
 
-    final session = await FFmpegKit.execute(command);
-    final returnCode = await session.getReturnCode();
+    final result = await _execute(command);
 
-    if (ReturnCode.isSuccess(returnCode)) {
+    if (result.success) {
       // Delete original M4A file
       try {
         await File(inputPath).delete();
@@ -27,12 +44,7 @@ class FFmpegService {
       return outputPath;
     }
 
-    // Log error for debugging
-    final logs = await session.getLogs();
-    for (final log in logs) {
-      _log.d(log.getMessage());
-    }
-
+    _log.e('M4A to FLAC conversion failed: ${result.output}');
     return null;
   }
 
@@ -54,13 +66,13 @@ class FFmpegService {
     final command =
         '-i "$inputPath" -codec:a libmp3lame -b:a $bitrate -map 0:a -map_metadata 0 -id3v2_version 3 "$outputPath" -y';
 
-    final session = await FFmpegKit.execute(command);
-    final returnCode = await session.getReturnCode();
+    final result = await _execute(command);
 
-    if (ReturnCode.isSuccess(returnCode)) {
+    if (result.success) {
       return outputPath;
     }
 
+    _log.e('FLAC to MP3 conversion failed: ${result.output}');
     return null;
   }
 
@@ -91,22 +103,21 @@ class FFmpegService {
           '-i "$inputPath" -codec:a aac -b:a $bitrate -map 0:a -map_metadata 0 "$outputPath" -y';
     }
 
-    final session = await FFmpegKit.execute(command);
-    final returnCode = await session.getReturnCode();
+    final result = await _execute(command);
 
-    if (ReturnCode.isSuccess(returnCode)) {
+    if (result.success) {
       return outputPath;
     }
 
+    _log.e('FLAC to M4A conversion failed: ${result.output}');
     return null;
   }
 
   /// Check if FFmpeg is available
   static Future<bool> isAvailable() async {
     try {
-      final session = await FFmpegKit.execute('-version');
-      final returnCode = await session.getReturnCode();
-      return ReturnCode.isSuccess(returnCode);
+      final version = await _channel.invokeMethod('getVersion');
+      return version != null && version.toString().isNotEmpty;
     } catch (e) {
       return false;
     }
@@ -115,11 +126,55 @@ class FFmpegService {
   /// Get FFmpeg version info
   static Future<String?> getVersion() async {
     try {
-      final session = await FFmpegKit.execute('-version');
-      final output = await session.getOutput();
-      return output;
+      final version = await _channel.invokeMethod('getVersion');
+      return version as String?;
     } catch (e) {
       return null;
     }
   }
+
+  /// Embed cover art to FLAC file
+  /// Returns the file path on success, null on failure
+  static Future<String?> embedCover(String flacPath, String coverPath) async {
+    final tempOutput = '$flacPath.tmp';
+    final command = '-i "$flacPath" -i "$coverPath" -map 0:a -map 1:0 -c copy -metadata:s:v title="Album cover" -metadata:s:v comment="Cover (front)" -disposition:v attached_pic "$tempOutput" -y';
+
+    final result = await _execute(command);
+
+    if (result.success) {
+      try {
+        // Replace original with temp
+        await File(flacPath).delete();
+        await File(tempOutput).rename(flacPath);
+        return flacPath;
+      } catch (e) {
+        _log.e('Failed to replace file after cover embed: $e');
+        return null;
+      }
+    }
+
+    // Clean up temp file if exists
+    try {
+      final tempFile = File(tempOutput);
+      if (await tempFile.exists()) {
+        await tempFile.delete();
+      }
+    } catch (_) {}
+
+    _log.e('Cover embed failed: ${result.output}');
+    return null;
+  }
+}
+
+/// Result of FFmpeg command execution
+class FFmpegResult {
+  final bool success;
+  final int returnCode;
+  final String output;
+
+  FFmpegResult({
+    required this.success,
+    required this.returnCode,
+    required this.output,
+  });
 }