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/view/guid_diff.cpp

@@ -41,4 +41,4 @@ void GuidBaseline::reset() {
     primed_ = false;  // next observe() re-baselines (first-poll guard re-armed)
 }
 
-}  // namespace reasampler::view
+}  // namespace reasampler::view