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/trigger_seam.cpp

@@ -24,4 +24,4 @@ std::int64_t fadeFractionToFrames(double fadeFraction, std::int64_t playLength)
     return static_cast<std::int64_t>(fadeFraction * static_cast<double>(playLength) + 0.5);
 }
 
-}  // namespace reasampler::instrument::map
+}  // namespace reasampler::instrument::map