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/theme.cpp

@@ -190,4 +190,4 @@ double textFloor(TextClass cls) {
     return cls == TextClass::Body ? 4.5 : 3.0;
 }
 
-} // namespace reasampler::ui
+} // namespace reasampler::ui