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/model/bank_model.cpp

@@ -458,4 +458,4 @@ std::optional<BankModel> BankModel::deserialize(const std::string& blob) {
     return idx;
 }
 
-} // namespace reasampler::model
+} // namespace reasampler::model