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/ui/embed_strip.cpp

@@ -83,4 +83,4 @@ Rect levelFillRect(const EmbedLayout& layout, double level) {
     return Rect::ltrb(band.x, band.y, band.x + fillW, band.bottom());
 }
 
-}  // namespace reasampler::instrument::ui
+}  // namespace reasampler::instrument::ui