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/wav_trim.h

@@ -100,4 +100,4 @@ struct WavTruncatePlan {
 // truncate the file to newFileByteLength.
 WavTruncatePlan planWavTruncate(const WavLayout& layout, std::size_t keptFrames);
 
-} // namespace reasampler::capture
+} // namespace reasampler::capture