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/ui/card_meta.h

@@ -52,4 +52,4 @@ std::string formatBarsBeats(const MusicalLength& m);
 //   * negative length is clamped to "0.000" (a length is never negative; defensive).
 std::string formatSecondsMs(double lengthSeconds);
 
-} // namespace reasampler::ui
+} // namespace reasampler::ui