refactor(file): download 方法复用 resolveBaseDir，统一目录创建逻辑

sdk-core/src/main/java/com/xuqm/sdk/file/FileSDK.kt

@@ -165,13 +165,7 @@ object FileSDK {
             ?: "download.bin"
 
         val baseDir = when (destination) {
-            FileDownloadDestination.PublicDownloads -> {
+            FileDownloadDestination.PublicDownloads -> resolveBaseDir(context, destination)
-                val appName = context.applicationInfo.loadLabel(context.packageManager).toString()
-                File(
-                    Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS),
-                    appName,
-                ).apply { mkdirs() }
-            }
             FileDownloadDestination.Sandbox -> {
                 if (directoryName.isNullOrBlank()) {
                     context.getExternalFilesDir(null) ?: context.filesDir