fix(file): resolveBaseDir 多重尝试创建目录，兼容华为/小米设备

- mkdirs() 静默失败时，尝试 Runtime.exec('mkdir -p')
- 仍失败则回退到 Sandbox 目录，避免 ENOENT 崩溃

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

@@ -278,12 +278,25 @@ object FileSDK {
     private fun resolveBaseDir(context: Context, destination: FileDownloadDestination): File = when (destination) {
         FileDownloadDestination.PublicDownloads -> {
             val appName = context.applicationInfo.loadLabel(context.packageManager).toString()
-            File(
+            val dir = File(
                 android.os.Environment.getExternalStoragePublicDirectory(
                     android.os.Environment.DIRECTORY_DOWNLOADS
                 ),
                 appName,
-            ).apply { mkdirs() }
+            )
+            // mkdirs() 在部分华为/小米设备上静默失败，多重尝试确保目录存在
+            if (!dir.exists()) {
+                dir.mkdirs()
+            }
+            if (!dir.exists()) {
+                runCatching { Runtime.getRuntime().exec(arrayOf("mkdir", "-p", dir.absolutePath)).waitFor() }
+            }
+            if (!dir.exists()) {
+                android.util.Log.w("XWV", "resolveBaseDir: cannot create ${dir.absolutePath}, falling back to Sandbox")
+                context.getExternalFilesDir(null) ?: context.filesDir
+            } else {
+                dir
+            }
         }
         FileDownloadDestination.Sandbox -> {
             context.getExternalFilesDir(null) ?: context.filesDir