Q-W1 code-review follow-ups: restore 104 trailing newlines, relocate reasampler_uid.h to core/wire, drop ext_keys namespaces shim, add slot_map_tests, golden serialize literals for 4 modules, namespaces.h/pragma-once ordering sweep. 60/60 green.

src/core/capture/tail_control.cpp

@@ -128,4 +128,4 @@ std::optional<TailSetting> deserializeTailSetting(const std::string& blob) {
     return out;
 }
 
-} // namespace reasampler::capture
+} // namespace reasampler::capture