source: DataSource, Frame, SourceConfig and the registry (unused yet)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CMakeLists.txt

@@ -236,6 +236,9 @@ add_executable(udpscope
   src/waveform.cpp
   src/event_store.cpp
   src/acquisition.cpp
+  src/source/source_config.cpp
+  src/source/data_source.cpp
+  src/source/registry.cpp
   src/plot_host.cpp
   src/export.cpp
   src/search.cpp