docs: add support for yarn, pnpm, and bun in setup environment section

[AkshayRaj1999]

☕️ Reasoning

Changes

• Wrapped npx auth secret command in Code component with npm2yarn directive
• Added framework-specific tabs (Next, Qwik, Svelte, Express) for consistency
• Maintained consistency with the existing "Installing Auth.js" section pattern
• Kept bun alternative separate as it uses bunx instead of npx

🧢 Checklist

• [Yes ] Documentation
• [ ] Tests
• [ ] Ready to be merged

🎫 Affected issues

📌 Resources

• Security guidelines
• Contributing guidelines
• Code of conduct
• Contributing to Open Source

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Project	Deployment	Preview	Comments	Updated (UTC)
auth-docs	Error			Oct 22, 2025 7:44am

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Project	Deployment	Preview	Comments	Updated (UTC)
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