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/capture/insert_plan.h

@@ -72,4 +72,4 @@ int computeInsertMode(const InsertOptions& opts);
 // any computed mode (the "no silent time-stretch" invariant, made checkable).
 inline constexpr int kStretchToTimeSelBit = 4;
 
-} // namespace reasampler::capture
+} // namespace reasampler::capture