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/instrument/map/bridge_marshal.cpp

@@ -13,4 +13,4 @@ std::optional<std::string> decodeGetProjExtState(int apiReturn,
     return buffer;
 }
 
-}  // namespace reasampler::instrument::map
+}  // namespace reasampler::instrument::map