Make role-change report saved value on-screen

@bind:after did not persist reliably. Move back to an explicit @onchange
handler and surface every outcome in the page alert, including the role
re-read from the store after the write. This makes a failed save visible
(unrecognized value, exception, or saved != selected) instead of silent,
so we can pinpoint where the role update breaks.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Components/Pages/Admin/UserManagement.razor

@@ -86,11 +86,12 @@ else
                         </td>
                         <td style="padding:8px">
                             <select class="form-input" style="width:130px"
-                                    @bind="user.Role" @bind:after="() => PersistRoleAsync(user)"
+                                    value="@user.Role"
+                                    @onchange="@(e => OnRoleChange(user, e))"
                                     disabled="@(user.Email == UserContext.Email)">
                                 @foreach (var role in Enum.GetValues<UserRole>())
                                 {
-                                    <option value="@role">@role</option>
+                                    <option value="@role" selected="@(user.Role == role)">@role</option>
                                 }
                             </select>
                         </td>
@@ -192,16 +193,26 @@ else
         }
     }
 
-    // Bound via @bind:after, so user.Role already holds the newly-selected value when this runs.
+    private async Task OnRoleChange(AppUser user, ChangeEventArgs e)
-    private async Task PersistRoleAsync(AppUser user)
     {
+        // Surface every branch on-screen so a failed save is never silent. The "saved" value is
+        // re-read from the store, so it proves whether the write actually landed on disk.
+        var raw = e.Value?.ToString();
+        if (!Enum.TryParse<UserRole>(raw, out var newRole))
+        {
+            _message = string.Format(T["usermgmt.msg.error"], $"unrecognized role value '{raw}'");
+            _isError = true;
+            return;
+        }
         try
         {
-            var oldRole = await UserService.UpdateRoleAsync(user.Id, user.Role);
+            var oldRole = await UserService.UpdateRoleAsync(user.Id, newRole);
+            user.Role   = newRole;
+            var saved   = (await UserService.GetByEmailAsync(user.Email))?.Role;
             await Audit.LogAsync("RoleChanged", "", Array.Empty<string>(),
-                $"Changed role for {user.Email} ({user.DisplayName}) from {oldRole} to {user.Role}.");
+                $"Changed role for {user.Email} ({user.DisplayName}) from {oldRole} to {newRole}.");
-            _message  = string.Format(T["usermgmt.msg.roleupdated"], user.DisplayName);
+            _message  = $"{string.Format(T["usermgmt.msg.roleupdated"], user.DisplayName)} ({oldRole} → {newRole}, saved: {saved})";
-            _isError  = false;
+            _isError  = saved != newRole;
         }
         catch (Exception ex)
         {