- Add cbt::window class in cbt/ directory with RAII lifecycle
- Add setup_opengl and info_opengl for glad init and GL info
- Add Q key to quit the application
- Update CMakeLists.txt with glfw3 and glad dependencies
- Update AGENTS.md with snake_case naming and shell conventions
- Add include ordering rules: C++ std, C std, OS-specific,
third-party, local headers (separated by blank lines)
- Clarify <> for system headers, "" for third-party deps
- Remove .exe from run command
- Mark shell code blocks as sh (POSIX compliant)
- Add shell script conventions section