[nostalgia] Add basic support for subsheets

src/nostalgia/core/CMakeLists.txt

@@ -45,8 +45,8 @@ else()
 	)
 endif()
 
-set(
-	NOSTALGIA_CORE_GENERAL_SRC
+add_library(
+	NostalgiaCore-Common OBJECT
 		gfx.cpp
 		media.cpp
 		typeconv.cpp
@@ -54,33 +54,35 @@ set(
 
 add_library(
 	NostalgiaCore
-		${NOSTALGIA_CORE_GENERAL_SRC}
 		${NOSTALGIA_CORE_IMPL_SRC}
 )
 
 add_library(
 	NostalgiaCore-Headless
-		${NOSTALGIA_CORE_GENERAL_SRC}
 		headless/core.cpp
 		headless/gfx.cpp
 		headless/media.cpp
 )
 
 if(NOT MSVC)
-	target_compile_options(NostalgiaCore PUBLIC -Wsign-conversion)
+	target_compile_options(NostalgiaCore-Common PUBLIC -Wsign-conversion)
 endif()
 
 target_link_libraries(
-	NostalgiaCore PUBLIC
+	NostalgiaCore-Common PUBLIC
 		OxClaw
 		OxFS
+)
+
+target_link_libraries(
+	NostalgiaCore PUBLIC
+		NostalgiaCore-Common
 		${NOSTALGIA_CORE_IMPL_LIBS}
 )
 
 target_link_libraries(
 	NostalgiaCore-Headless PUBLIC
-		OxClaw
-		OxFS
+		NostalgiaCore-Common
 )
 
 if(NOSTALGIA_BUILD_STUDIO)