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/shell/actions/drag_out_win.h

@@ -1,5 +1,5 @@
-#include "core/namespaces.h"
 #pragma once
+#include "core/namespaces.h"
 // drag_out_win — the OS/COM initiation half of native OS drag-out (Milestone 11). The pure
 // gesture-boundary decision and path-list assembly live in drag_out.*; THIS is the platform
 // shell that hands a resolved, existing-file path list to the operating system's drag-drop

src/shell/actions/instrument_drop_win.h

@@ -1,5 +1,5 @@
-#include "core/namespaces.h"
 #pragma once
+#include "core/namespaces.h"
 // instrument_drop_win — the REAPER-facing shell half of S17 drop-and-load. The pure gesture
 // decision lives in drag_out (DragGesture::InstrumentDrop) and the pure payload construction
 // in instrument_drop; THIS is the platform shell that (a) resolves a screen point to a track