v2.18.1

Republishes the legacy mirrors (react-native-ai-devtools, react-native-ai-debugger), which missed 2.18.0 after a transient Sigstore 502 during the mirror publish. No changes to the server itself.

• ci(publish): each publish step skips a version already on npm, so a run that fails part-way can be re-run instead of needing a new version.