e1608: link and device layers (discovery, handshake, framed commands, calibration, decode)

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

CMakeLists.txt

@@ -242,6 +242,8 @@ add_executable(udpscope
   src/source/udps_source.cpp
   src/source/udps_kind.cpp
   src/source/probe_source.cpp
+  src/source/e1608/e1608_link.cpp
+  src/source/e1608/e1608_device.cpp
   src/plot_host.cpp
   src/export.cpp
   src/search.cpp