docs: replace deprecated yarn global examples

[SSDWGG]

Summary

• replace deprecated yarn global add examples with yarn dlx commands
• update language-server, formatter, linter, and editor integration docs

Fixes #1312

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve a real Yarn install step

When a Yarn user follows this editor setup, this command starts the language server once instead of installing herb-language-server onto PATH: Yarn's dlx docs describe it as running a package in a temporary environment. The subsequent instructions on this page and the editor-specific pages still run or configure herb-language-server --stdio, so they fail in a fresh shell for Yarn-only users; either keep an actual installation path or update the editor commands to invoke Yarn each time.

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