build: bump transformer-engine to release_v2.16_post

[ko3n1g]

Background

• Bump TransformerEngine to release_v2.16_post to pick up the latest fixes on the 2.16 line.

What changed

• Bump transformer-engine git pin in [tool.uv.sources].
• Regenerate uv.lock.

Details

• pyproject.toml: rev 4220403e → d64bc14d — the resolved HEAD of TE release_v2.16_post, pinned as a full SHA for reproducibility.
• uv.lock: only the TE source/git refs move to the new rev; no other resolution changes (2 files, 8 lines total).

Tested

• uv lock regenerated cleanly inside the CI dev container (uv 0.7.2); diff limited to the TE rev.
• CI: Run functional tests + container::lts — a TE bump can shift training numerics, so exercise the golden-value compare on both image variants.

Cherry-pick

• Labeled core_r0.18.0 for auto-cherrypick to the release branch after merge.

[github-actions]

This PR has been automatically converted to draft because all PRs must start as drafts.

When you are ready for review, click Ready for Review to begin the review process. This will:

1. Add the oncall reviewer (optional reviewer)
2. Add required review teams based on your changes

See the contribution guide for more details.

[copy-pr-bot]

Auto-sync is disabled for draft pull requests in this repository. Workflows must be run manually.

Contributors can view more details about this message here.

[ko3n1g]

/ok to test fc3817e

[svcnvidia-nemo-ci]

🔄 Merge queue validation started!

You can track the progress here: https://github.com/NVIDIA/Megatron-LM/actions/runs/28260354930

[svcnvidia-nemo-ci]

🔄 Merge queue validation started!

You can track the progress here: https://github.com/NVIDIA/Megatron-LM/actions/runs/28267788935

[ko3n1g]

Superseded by #5517, which pins the release_v2.16.post (dotted) branch head instead of release_v2.16_post.