✨ feat(file-check): 添加 PLC 应答后命中文件删除

* 新增默认关闭的删除开关，仅在收到 PLC 放行应答后执行

* 本地与 SFTP Provider 校验根目录并支持幂等删除

* 补充工作流、设置页和文件删除相关测试与文档

tests/AxiOmron.PcbCheck.Tests/LocalFileCheckProviderTests.cs

@@ -124,6 +124,56 @@ public sealed class LocalFileCheckProviderTests : IDisposable
         Assert.Equal(filePath, outcome.MatchedFilePath);
     }
 
+    /// <summary>
+    /// 删除目标位于配置根目录内时，应删除文件并返回成功。
+    /// </summary>
+    /// <returns>异步测试任务。</returns>
+    [Fact]
+    public async Task DeleteFileAsync_ShouldDeleteFile_WhenFileIsWithinConfiguredRoot()
+    {
+        string filePath = Path.Combine(_rootPath, "PCB-DELETE-001.txt");
+        await File.WriteAllTextAsync(filePath, "ok");
+        var provider = CreateProvider();
+
+        FileDeleteOutcome outcome = await provider.DeleteFileAsync(
+            filePath,
+            CreateConfig(_rootPath),
+            CancellationToken.None);
+
+        Assert.True(outcome.IsSuccess);
+        Assert.False(outcome.WasAlreadyMissing);
+        Assert.False(File.Exists(filePath));
+    }
+
+    /// <summary>
+    /// 删除目标位于配置根目录之外时，应拒绝删除以防止误删其他文件。
+    /// </summary>
+    /// <returns>异步测试任务。</returns>
+    [Fact]
+    public async Task DeleteFileAsync_ShouldRejectFile_WhenFileIsOutsideConfiguredRoot()
+    {
+        string parentPath = Directory.GetParent(_rootPath)!.FullName;
+        string filePath = Path.Combine(parentPath, $"{Guid.NewGuid():N}.txt");
+        await File.WriteAllTextAsync(filePath, "keep");
+        var provider = CreateProvider();
+
+        try
+        {
+            FileDeleteOutcome outcome = await provider.DeleteFileAsync(
+                filePath,
+                CreateConfig(_rootPath),
+                CancellationToken.None);
+
+            Assert.False(outcome.IsSuccess);
+            Assert.Contains("根目录之外", outcome.ErrorMessage);
+            Assert.True(File.Exists(filePath));
+        }
+        finally
+        {
+            File.Delete(filePath);
+        }
+    }
+
     /// <summary>
     /// 创建本地文件校验提供程序。
     /// </summary>