feat: 添加目录存在性检查并优化复制逻辑

- 添加目录存在性检查功能并更新复制逻辑以使用该功能

apps/desktop/copy.ts

@@ -159,6 +159,9 @@ class FileSystemService extends Context.Tag('FileSystemService')<
     readonly fileExists: (
       filePath: string,
     ) => Effect.Effect<boolean, FileSystemError>
+    readonly dirExists: (
+      dirPath: string,
+    ) => Effect.Effect<boolean, FileSystemError>
     readonly copyFile: (
       source: string,
       target: string,
@@ -193,6 +196,25 @@ class FileSystemService extends Context.Tag('FileSystemService')<
           }),
       }),
 
+    dirExists: (dirPath: string) =>
+      Effect.tryPromise({
+        try: async () => {
+          const { default: fs } = await import('node:fs/promises')
+          try {
+            const stat = await fs.stat(dirPath)
+            return stat.isDirectory()
+          } catch {
+            return false
+          }
+        },
+        catch: (cause: unknown) =>
+          new FileSystemError({
+            operation: 'dirExists',
+            path: dirPath,
+            cause,
+          }),
+      }),
+
     copyFile: (source: string, target: string) =>
       Effect.tryPromise({
         try: async () => {
@@ -381,7 +403,7 @@ const program = Effect.gen(function* () {
   yield* Console.log('📦 开始复制二进制文件到 Tauri sidecar 目录...\n')
 
   // 1. 检查源目录
-  const sourceExists = yield* fs.fileExists(config.sourceDir)
+  const sourceExists = yield* fs.dirExists(config.sourceDir)
   if (!sourceExists) {
     yield* Console.error(`❌ 源目录不存在: ${config.sourceDir}`)
     yield* Console.log(