State in the README and NOTICE that this is a contest entry derived from
StarryOS, name the baseline commit and split the licence scope between
upstream code (Apache-2.0) and contest documents (CC-BY-SA 4.0). Correct
the obsolete `git submodule` and clippy instructions that no longer match
the repository, so contributors do not chase a pre-existing failure.

AI-Assisted: Claude Code / deepseek-flash[1m]
AI-Scope: 文档起草