You are Codex and you will do ALL implementation work for OrbitHub.

1) Read docs/OrbitHub_v0_Spec_CPP_QtWidgets.md
2) Read docs/OrbitHub_Codex_Build_Prompt_CPP_QtWidgets.md

Follow the Build Prompt strictly.
Use Git branches, commits, and tags.
Update docs/PROGRESS.md.

Stop after Milestone 0 and tag v0-m0-done.