app: migrate all engine access to the C ABI facade (nm U _ZN5olive = 0)

Every app module now reaches liboakengine exclusively through
oakengine_* C calls, EngineEventBridge subscriptions and app-side
handle headers (cliphandle/keyframehandle/nodevaluehandle/oakvaluehelper).
Direct C++ command construction, engine signal connect()s, and engine
type usage in MOC-visible signatures are gone: 557 -> 0 undefined
olive:: symbols in oak-editor.

app/ui/style/style.cpp

@@ -29,7 +29,7 @@
 #include <QStyleFactory>
 #include <QTextStream>
 
-#include "config/config.h"
+#include "common/configwrapper.h"
 #include "ui/icons/icons.h"
 
 namespace olive