Unify the config folder name to `.opencodereview` across all runtime paths,
tests, docs, and i18n strings. Also make defaultConfigPath() return an error
instead of silently falling back to a current-directory file when $HOME is
unresolvable.
The commit updates the npm package name from `open-code-review` to `@alibaba-group/open-code-review` in both QuickStartSection and DocsPage components to reflect the correct package identifier.