Add Bazel build support

[yanyiwu]

Summary

• add Bzlmod metadata and public Bazel targets for cppjieba, vendored limonp, and dictionary files
• add a small Bazel smoke test that constructs cppjieba::Jieba with runfile dictionary paths
• add a Bazel GitHub Actions workflow to keep the new build path covered

Validation

• npx --yes @bazel/bazelisk test --cache_test_results=no //:bazel_smoke_test

Closes #233