docs: make the bilingual user guide easier to follow

[yi-ge]

Summary

• Add task-first navigation so readers can jump directly to common tasks.
• Simplify Chinese and English user-guide wording while preserving examples, analogies, and useful explanations.
• Align operation steps and status guidance with the current interface; remove unsupported shortcut and recovery claims.
• Clarify model routing, account and invoice flows, memory scope, app installation, document review, and task recovery.
• Fix broken Linux installation anchors and clarify historical provider examples.

Validation

• Docusaurus production build succeeded for zh-Hans and en.
• git diff --check passed; changed Markdown pages have matching English counterparts and local links resolve.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
docs	Ready	Preview	Oct 3, 2026 4:04pm UTC