chore(release): bump kimi-cli and kimi-code to 1.43.0 - #2244

Summary

• Bump kimi-cli and kimi-code to 1.43.0
• Move the current release notes under 1.43.0

Validation

• uv run python scripts/check_version_tag.py --pyproject pyproject.toml --expected-version 1.43.0
• uv run python scripts/check_version_tag.py --pyproject packages/kimi-code/pyproject.toml --expected-version 1.43.0
• uv run python scripts/check_kimi_dependency_versions.py --root-pyproject pyproject.toml --kosong-pyproject packages/kosong/pyproject.toml --pykaos-pyproject packages/kaos/pyproject.toml
• make check

Post-merge

After this PR lands, create and push the release tag:

git tag 1.43.0
git push origin 1.43.0