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/engine/velocity_curve.cpp

@@ -269,4 +269,4 @@ bool VelocityCurve::equals(const VelocityCurve& other, double eps) const {
     return true;
 }
 
-}  // namespace reasampler::instrument::engine
+}  // namespace reasampler::instrument::engine