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/audio/peaks.cpp

@@ -123,4 +123,4 @@ std::size_t lastFrameAboveThreshold(const std::vector<AudioSample>& interleaved,
     return kNoFrameAboveThreshold;
 }
 
-} // namespace reasampler::audio
+} // namespace reasampler::audio

src/core/audio/peaks.h

@@ -119,4 +119,4 @@ std::size_t lastFrameAboveThreshold(const std::vector<AudioSample>& interleaved,
                                     std::size_t frameCount,
                                     AudioSample linearThreshold);
 
-} // namespace reasampler::audio
+} // namespace reasampler::audio