build: drop lib prefix from oakgl/oakvulkan DLLs on Windows

MinGW CMake defaults to prefixing shared libraries with 'lib', producing liboakgl.dll which the dynamic backend loader cannot find. Set PREFIX empty on Windows so the output names match the runtime names oakgl.dll / oakvulkan.dll.

app/CMakeLists.txt

@@ -155,6 +155,9 @@ if (OAK_ENABLE_DYNAMIC_RENDER_BACKEND)
     RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
     ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
   )
+  if(WIN32)
+    set_target_properties(oakgl PROPERTIES PREFIX "")
+  endif()
   install(TARGETS oakgl
     RUNTIME DESTINATION bin
     LIBRARY DESTINATION lib
@@ -181,6 +184,9 @@ if (OAK_ENABLE_DYNAMIC_RENDER_BACKEND)
       RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
       ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
     )
+    if(WIN32)
+      set_target_properties(oakvulkan PROPERTIES PREFIX "")
+    endif()
     install(TARGETS oakvulkan
       RUNTIME DESTINATION bin
       LIBRARY DESTINATION lib