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/curve_popup.cpp

@@ -38,4 +38,4 @@ bool popupOutsideSheet(const CurvePopupLayout& layout, int x, int y) {
     return !contains(layout.sheet, x, y);
 }
 
-}  // namespace reasampler::instrument::ui
+}  // namespace reasampler::instrument::ui