feat: add cross-engine platform services

Runtime/LocalStorageProvider.cs

@@ -3,8 +3,8 @@ using System.Collections.Concurrent;
 using System.IO;
 using System.Linq;
 using System.Threading;
+using System.Threading.Tasks;
 using Cysharp.Threading.Tasks;
-using UnityEngine;
 
 namespace ShrinkDataSaver
 {
@@ -21,7 +21,11 @@ namespace ShrinkDataSaver
 
         public LocalStorageProvider(string rootPath = null)
         {
-            _rootPath = rootPath ?? Application.persistentDataPath;
+            _rootPath = rootPath ?? ShrinkDataSaverPlatform.Paths?.PersistentDataPath
+#if UNITY_5_3_OR_NEWER
+                ?? UnityEngine.Application.persistentDataPath
+#endif
+                ?? throw new InvalidOperationException("ShrinkDataSaver persistent path is not configured.");
         }
 
         private string Resolve(string path) =>
@@ -33,7 +37,7 @@ namespace ShrinkDataSaver
             var dir = Path.GetDirectoryName(fullPath);
             if (!string.IsNullOrEmpty(dir))
             {
-                await UniTask.RunOnThreadPool(() => Directory.CreateDirectory(dir), cancellationToken: ct);
+                await Task.Run(() => Directory.CreateDirectory(dir), ct);
             }
 
             var tempPath = fullPath + TempWriteSuffix;
@@ -45,7 +49,7 @@ namespace ShrinkDataSaver
             try
             {
                 await WriteFileBytesAsync(tempPath, data, ct);
-                await UniTask.RunOnThreadPool(() =>
+                await Task.Run(() =>
                 {
                     if (File.Exists(fullPath))
                     {
@@ -65,17 +69,17 @@ namespace ShrinkDataSaver
                     {
                         File.Move(tempPath, fullPath);
                     }
-                }, cancellationToken: ct);
+                }, ct);
             }
             catch
             {
-                await UniTask.RunOnThreadPool(() =>
+                await Task.Run(() =>
                 {
                     if (File.Exists(tempPath))
                     {
                         File.Delete(tempPath);
                     }
-                }, cancellationToken: CancellationToken.None);
+                }, CancellationToken.None);
                 throw;
             }
             finally
@@ -105,7 +109,7 @@ namespace ShrinkDataSaver
         }
 
         public UniTask<bool> ExistsAsync(string path, CancellationToken ct = default) =>
-            UniTask.RunOnThreadPool(() => File.Exists(Resolve(path)), cancellationToken: ct);
+            Task.Run(() => File.Exists(Resolve(path)), ct).AsUniTask();
 
         public async UniTask DeleteAsync(string path, CancellationToken ct = default)
         {
@@ -114,13 +118,13 @@ namespace ShrinkDataSaver
             await pathLock.WaitAsync(ct);
             try
             {
-                await UniTask.RunOnThreadPool(() =>
+                await Task.Run(() =>
                 {
                     if (File.Exists(fullPath))
                     {
                         File.Delete(fullPath);
                     }
-                }, cancellationToken: ct);
+                }, ct);
             }
             finally
             {
@@ -130,7 +134,7 @@ namespace ShrinkDataSaver
 
         public async UniTask<string[]> ListAsync(string prefix = "", CancellationToken ct = default)
         {
-            return await UniTask.RunOnThreadPool(() =>
+            return await Task.Run(() =>
             {
                 var dir = string.IsNullOrEmpty(prefix) ? _rootPath : Path.Combine(_rootPath, prefix);
                 if (!Directory.Exists(dir))
@@ -141,7 +145,7 @@ namespace ShrinkDataSaver
                 return Directory.GetFiles(dir)
                     .Select(f => Path.GetRelativePath(_rootPath, f))
                     .ToArray();
-            }, cancellationToken: ct);
+            }, ct);
         }
 
         private static SemaphoreSlim GetPathLock(string fullPath)