launcher: Photon AppId setup walkthrough

The two empty "REALTIME APPID / VOICE APPID" textboxes assumed the
user already knew what Photon was, where to sign up, and which app
type to create. New 5-step wizard fills that gap:

1. What's Photon? — one-paragraph explanation tying back to DorkNet
2. Make an account — Open Dashboard button launches browser
3. Create a Realtime app — numbered click-by-click instructions
4. Create a Voice app — same, with a Skip button (voice is optional)
5. Paste your AppIds — text fields with live regex validation,
   region picker, Save commits to AppState

Hyphens optional on input; we normalise to canonical 8-4-4-4-12 form
before writing back. The existing Photon section keeps its three
fields for advanced users, with a "Setup walkthrough" button at the
top opening the wizard prefilled with current values.

launcher/MainWindow.xaml.cs

@@ -231,6 +231,22 @@ public partial class MainWindow : Window
         _state.Save();
     }
 
+    private void OnOpenPhotonWizard(object sender, RoutedEventArgs e)
+    {
+        var wiz = new PhotonWizard(_state.PhotonAppId, _state.PhotonVoiceAppId, _state.PhotonRegion)
+        {
+            Owner = this,
+        };
+        if (wiz.ShowDialog() == true && wiz.Result is not null)
+        {
+            _state.PhotonAppId = wiz.Result.RealtimeAppId;
+            _state.PhotonVoiceAppId = wiz.Result.VoiceAppId;
+            _state.PhotonRegion = wiz.Result.Region;
+            _state.Save();
+            ReflectStateInUi();
+        }
+    }
+
     private void OnHostingModeChanged(object sender, RoutedEventArgs e)
     {
         // RadioButton.Checked fires twice on selection-change (once for