e1608: the settings, the DataSource state machine, and the connect form

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

src/source/registry.hpp

@@ -21,9 +21,10 @@ const std::vector<SourceKind*>& kinds();
 /// may drop. A later `dlopen` loader would only call `register_kind()`.
 void register_builtin_sources();
 
-/// The built-in kinds, each defined in its own file (`udps_kind.cpp`, `probe_source.cpp`).
+/// The built-in kinds, each defined in its own file (`udps_kind.cpp`, `probe_source.cpp`, `e1608/e1608_kind.cpp`).
 std::unique_ptr<SourceKind> make_udps_kind();
 std::unique_ptr<SourceKind> make_probe_kind();
+std::unique_ptr<SourceKind> make_e1608_kind();
 
 /// The (host, port) pair that names a source's session file. UDPS keeps its legacy
 /// `server`/`port`; any other kind is `"<kind>-<identity>"` (characters outside `[A-Za-z0-9._-]`