feat(04-06): implement TemplateService and FolderStructureService

- FolderStructureService.CreateFoldersAsync creates folder hierarchy from CSV rows using BulkOperationRunner
- FolderStructureService.BuildUniquePaths deduplicates and sorts paths parent-first by slash depth
- TemplateService already committed; verified compilation and interface compliance
- FolderStructureServiceTests: 4 unit tests pass (BuildUniquePaths edge cases, deduplication, empty levels, BuildPath) + 1 skip
- TemplateServiceTests: 3 unit tests pass (interface impl, SiteTemplate defaults, SiteTemplateOptions defaults) + 2 skip

SharepointToolbox.Tests/Services/TemplateServiceTests.cs

@@ -0,0 +1,49 @@
+using SharepointToolbox.Core.Models;
+using SharepointToolbox.Services;
+
+namespace SharepointToolbox.Tests.Services;
+
+public class TemplateServiceTests
+{
+    [Fact]
+    public void TemplateService_Implements_ITemplateService()
+    {
+        Assert.True(typeof(ITemplateService).IsAssignableFrom(typeof(TemplateService)));
+    }
+
+    [Fact]
+    public void SiteTemplate_DefaultValues_AreCorrect()
+    {
+        var template = new SiteTemplate();
+        Assert.NotNull(template.Id);
+        Assert.NotEmpty(template.Id);
+        Assert.NotNull(template.Libraries);
+        Assert.Empty(template.Libraries);
+        Assert.NotNull(template.PermissionGroups);
+        Assert.Empty(template.PermissionGroups);
+        Assert.NotNull(template.Options);
+    }
+
+    [Fact]
+    public void SiteTemplateOptions_AllDefaultTrue()
+    {
+        var opts = new SiteTemplateOptions();
+        Assert.True(opts.CaptureLibraries);
+        Assert.True(opts.CaptureFolders);
+        Assert.True(opts.CapturePermissionGroups);
+        Assert.True(opts.CaptureLogo);
+        Assert.True(opts.CaptureSettings);
+    }
+
+    [Fact(Skip = "Requires live SharePoint tenant")]
+    public async Task CaptureTemplateAsync_CapturesLibrariesAndFolders()
+    {
+        await Task.CompletedTask;
+    }
+
+    [Fact(Skip = "Requires live SharePoint admin context")]
+    public async Task ApplyTemplateAsync_CreatesTeamSiteWithStructure()
+    {
+        await Task.CompletedTask;
+    }
+}