feat(13-01): extend GraphDirectoryUser with UserType and add includeGuests parameter to directory service

- Add string? UserType as last positional parameter to GraphDirectoryUser record
- Add bool includeGuests = false parameter to IGraphUserDirectoryService.GetUsersAsync
- Branch Graph filter: members-only (default) vs all users when includeGuests=true
- Add userType to Graph Select array for MapUser population
- Update MapUser to include UserType from Graph User object
- Add MapUser_PopulatesUserType and MapUser_NullUserType tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

SharepointToolbox/Services/GraphUserDirectoryService.cs

@@ -22,6 +22,7 @@ public class GraphUserDirectoryService : IGraphUserDirectoryService
     /// <inheritdoc />
     public async Task<IReadOnlyList<GraphDirectoryUser>> GetUsersAsync(
         string clientId,
+        bool includeGuests = false,
         IProgress<int>? progress = null,
         CancellationToken ct = default)
     {
@@ -29,11 +30,12 @@ public class GraphUserDirectoryService : IGraphUserDirectoryService
 
         var response = await graphClient.Users.GetAsync(config =>
         {
-            // Pending real-tenant verification — see STATE.md pending todos
-            config.QueryParameters.Filter = "accountEnabled eq true and userType eq 'Member'";
+            config.QueryParameters.Filter = includeGuests
+                ? "accountEnabled eq true"
+                : "accountEnabled eq true and userType eq 'Member'";
             config.QueryParameters.Select = new[]
             {
-                "displayName", "userPrincipalName", "mail", "department", "jobTitle"
+                "displayName", "userPrincipalName", "mail", "department", "jobTitle", "userType"
             };
             config.QueryParameters.Top = 999;
             // No ConsistencyLevel header: standard equality filter does not require eventual consistency
@@ -74,5 +76,6 @@ public class GraphUserDirectoryService : IGraphUserDirectoryService
             UserPrincipalName: user.UserPrincipalName ?? string.Empty,
             Mail: user.Mail,
             Department: user.Department,
-            JobTitle: user.JobTitle);
+            JobTitle: user.JobTitle,
+            UserType: user.UserType);
 }

SharepointToolbox/Services/IGraphUserDirectoryService.cs

@@ -13,6 +13,10 @@ public interface IGraphUserDirectoryService
     /// Iterates through all pages using the Graph SDK PageIterator until exhausted or cancelled.
     /// </summary>
     /// <param name="clientId">The client/tenant identifier used to obtain a Graph token.</param>
+    /// <param name="includeGuests">
+    /// When <c>false</c> (default), only member users are returned (userType eq 'Member').
+    /// When <c>true</c>, both members and guests are returned (no userType filter).
+    /// </param>
     /// <param name="progress">
     /// Optional progress reporter — receives the running count of users fetched so far.
     /// Phase 13's ViewModel uses this to show "Loading... X users" feedback.
@@ -21,6 +25,7 @@ public interface IGraphUserDirectoryService
     /// <param name="ct">Cancellation token. Iteration stops when cancelled.</param>
     Task<IReadOnlyList<GraphDirectoryUser>> GetUsersAsync(
         string clientId,
+        bool includeGuests = false,
         IProgress<int>? progress = null,
         CancellationToken ct = default);
 }