[CI/Build][Rust Frontend] Retire Buf schema publishing

[JulienDarve]

Purpose

Retire the Buf Schema Registry publication path added in #51276, following the crates.io publishing support merged in #56365.

• Remove nightly, release, and manual Buf publication, token usage, and registry metadata.
• Keep protobuf build/lint checks on pull requests, including forks.
• Update the documentation to direct Rust consumers to vllm-proto and other consumers to the canonical .proto files.

Consumers following Buf labels will no longer receive schema or generated SDK updates through that channel.

Open-PR searches for Buf Schema Registry, buf publishing, 51276 in:body, and 56365 in:body found no duplicate retirement PR.

Test Plan

• buf build rust/proto
• buf lint rust/proto
• pre-commit run --files .github/workflows/buf.yml rust/proto/README.md rust/proto/buf.yaml
• git diff --check

Test Result

All checks passed with Buf CLI 1.72.0, including actionlint and Markdown lint.

Model evaluation was not run: this change affects publication and documentation only. The protobuf schemas, binding generator, and crates.io workflow are unchanged.

AI assistance: This change was implemented with assistance from OpenAI Codex.

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[BugenZhao]

[AUTOMATED] @codex review

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-15T23:39:00.460304Z	7568b2b	Manual request

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Can't wait for the next one!

Reviewed commit: 7568b2b4a4

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[BugenZhao]

/ci run

[github-actions]

✅ @JulienDarve, CI is now available for this PR.

• /ci run starts upstream CI; /amd-ci run starts AMD CI only.
• Your branch must contain every commit currently on its upstream target branch. Merge or rebase onto the latest target branch, then rerun the command. Append --allow-stale to a run command to test an outdated branch at your own risk.
• /ci retry retries failed jobs in the CI build for the current PR head. If the current head has no CI build, it starts a new CI build for the current head containing only jobs that failed in the latest earlier CI build for this PR.
• /amd-ci retry retries failed jobs in AMD CI for the current PR head. Use /amd-ci run when the current head has no AMD CI build.
• /ci cancel cancels scheduled or running CI builds for this PR branch; /amd-ci cancel does the same for AMD CI only.

[github-actions]

✅ Triggered Buildkite CI #89222 for commit 83ff59cf8ca9.

[BugenZhao]

Thanks!