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.h

@@ -67,4 +67,4 @@ std::string tailToggleLabel(const TailSetting& setting);
 std::string serializeTailSetting(const TailSetting& setting);
 std::optional<TailSetting> deserializeTailSetting(const std::string& json);
 
-} // namespace reasampler::capture
+} // namespace reasampler::capture