feat: add AI setup guide to quality guard

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Summary

• add an AI setup guide beside the Quality Guard page actions
• provide version-aware, safety-first prompts in Chinese and English
• support one-click copy with responsive light/dark dialog states
• keep the guide free of deployment-specific addresses and credentials

This gives new users a practical path to configure Quality Guard while directing agents to inspect the checked-out version and preserve existing egress settings.

Scope

Frontend only. No backend, Quality Guard policy, proxy, or runtime behavior changes.

Validation

• frontend production build
• targeted ESLint
• git diff --check
• responsive browser checks at 320, 375, 414, 768, and 1440 px
• light and dark themes
• copy interaction and copied state
• no horizontal overflow at tested widths