test(06): complete UAT - 0 passed, 3 issues, 7 skipped

Fix two pre-existing blockers found during UAT:
- ProfileManagementViewModel: add NotifyCanExecuteChanged on property changes
- SessionManager: open browser in openBrowserCallback (was no-op)

Remaining blocker: SitePickerDialog parsing error from PnP Framework.

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

SharepointToolbox/Services/SessionManager.cs

@@ -60,8 +60,11 @@ public class SessionManager : ISessionManager
                 clientId: profile.ClientId,
                 openBrowserCallback: (url, port) =>
                 {
-                    // The browser/WAM flow is handled by MSAL; this callback receives the
-                    // local redirect URL and port. No action needed here — MSAL opens the browser.
+                    System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo
+                    {
+                        FileName = url,
+                        UseShellExecute = true
+                    });
                 },
                 tokenCacheCallback: tokenCache =>
                 {