feat(cli): support yarn plugin commands via vp pm plugin

[jong-kyung]

Summary

Resolves#1539. Adds vp pm plugin for managing Yarn 2+ plugins, mirroring the vp pm cache pattern (warn-and-exit-0 on unsupported PMs).

Subcommands

• import <spec> — import a plugin from a known source
• import-from-sources [name] — build and import from sources
• list — list plugins on the registry
• runtime — list installed plugins
• remove <name> — remove a plugin
• check — find third-party plugins that differ from their own spec

Behavior

• Yarn 2+: dispatches to yarn plugin <subcommand>
• Yarn 1.x / npm / pnpm / bun: prints a warning, exits 0

[netlify]

✅ Deploy Preview for viteplus-preview canceled.

Name	Link
🔨 Latest commit	f735b37
🔍 Latest deploy log	https://app.netlify.com/projects/viteplus-preview/deploys/6a0185dd99f2e3000874e25f

[jong-kyung]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit:38f2b77cd4

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".

[jong-kyung]

@cursor review

[cursor]

Skipping Bugbot: Unable to authenticate your request. Please make sure Bugbot is properly installed and configured for this repository.

[jong-kyung]

@codex review

[chatgpt-codex-connector]

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

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".

[jong-kyung]

@fengmk2 CI failed on the macOS arm64 job, but it looks like a transient GitHub infra issue. Could you re-run the failed jobs?