6c1096fbb8
- Extract scenes_cube/scenes_sphere (and convenience 'scenes' interface) to scenes/CMakeLists.txt. - Main CMakeLists.txt now much cleaner (single add_subdirectory(scenes)). - Updated help text in cuber.cpp to clearly separate Flags vs Keys (less confusing 'S' section). - No behavior change; depth/viewport/state/post-processing fixes from earlier remain. Followed project conventions and AGENTS.md commit rules.