fix: 修复Bitmap并发回收闪退和缓存帧竞态问题

- lastValidBitmap/lastCaptureTime添加@Volatile确保多协程可见性
- safeRecycleLastValidBitmap()添加@Synchronized防止并发double-recycle
- 新增updateLastValidBitmap()原子替换缓存帧(synchronized)
- 新增compressCachedFrame()安全压缩缓存帧(synchronized)
- 新增safeCopyLastValidBitmap()安全复制缓存帧(synchronized)
- 替换所有直接访问lastValidBitmap的代码为synchronized方法调用
- 涉及方法: startMediaProjectionCapture/startAccessibilityScreenCapture/handleAndroid11ScreenshotFailure/captureWithMediaProjection/forceRefreshAndroid15Images
- 清理MainActivity和SocketIOManager中日志的emoji符号

app/src/main/java/com/hikoncont/MainActivity.kt

@@ -3729,11 +3729,11 @@ class MainActivity : AppCompatActivity() {
 
             // 检查MediaProjectionManager是否已初始化
             if (mediaProjectionManager == null) {
-                Log.e(TAG, "❌ MediaProjectionManager未初始化，重新初始化")
+                Log.e(TAG, "MediaProjectionManager未初始化，重新初始化")
                 mediaProjectionManager =
                     getSystemService(MEDIA_PROJECTION_SERVICE) as MediaProjectionManager
                 if (mediaProjectionManager == null) {
-                    Log.e(TAG, "❌ 重新初始化MediaProjectionManager失败")
+                    Log.e(TAG, "重新初始化MediaProjectionManager失败")
                     return
                 }
             }