feat: log discovered NDI sources

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

App/Sources/SourceListModel.swift

@@ -30,6 +30,7 @@ final class SourceListModel {
 
         Task { [weak self] in
             for await list in finder.sources {
+                Log.ndi.info("Sources: \(list.map(\.ndiName), privacy: .public)")
                 self?.sources = list.sorted { $0.ndiName.localizedStandardCompare($1.ndiName) == .orderedAscending }
             }
         }