Add debug logging for raw Starface API contact data

Logs the first contact from Starface API response into the sync
log so we can see the actual JSON structure and fix field mapping.

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

src/StarfaceOutlookSync/Services/SyncEngine.cs

@@ -53,6 +53,7 @@ namespace StarfaceOutlookSync.Services
                 Log("Verbinde mit Starface...");
                 using (var starface = new StarfaceApiClient(profile.StarfaceConnection))
                 {
+                    starface.OnDebug += (msg) => Log(msg);
                     var loginOk = await starface.LoginAsync();
                     if (!loginOk)
                     {