Add the renderer process

The renderer becomes two programs: the adapter (t5deRenderEngine.dll, 32-bit, in IMVU's process) and a 64-bit renderer process (t5de-renderer.exe) drawing with Diligent Engine, fetched with FetchContent and pinned. For now a spike: the adapter starts the renderer process for each engine and signals each frame through a shared memory channel, and the renderer process draws a box into a child window in the client's 3D view.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

adapter/CMakeLists.txt

@@ -0,0 +1,12 @@
+# t5deRenderEngine.dll, the adapter: a renderer plugin for IMVU Classic (32-bit).
+
+add_library(t5de_render_engine SHARED
+    log.cpp
+    passthrough_engine.cpp
+    plugin.cpp
+    plugin.def
+    renderer_process.cpp)
+set_target_properties(t5de_render_engine PROPERTIES OUTPUT_NAME t5deRenderEngine)
+target_link_libraries(t5de_render_engine PRIVATE t5de::imvu t5de::protocol t5de::options)
+
+install(TARGETS t5de_render_engine RUNTIME DESTINATION .)