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/action_bar.cpp

@@ -151,4 +151,4 @@ int hitTestActionBar(int px, int py, const ActionBarRect& bar,
     return -1;  // inter-button/cluster gap or the overflow dead-zone — a clean miss
 }
 
-} // namespace reasampler::ui
+} // namespace reasampler::ui