新增LX FAQ，调整部分内容和链接

[fr1g]

此外还调整了部分样式以优化可读性

---

PR-Codex overview

This PR focuses on updates to documentation and styling in the project. It includes new content for FAQs, adjustments in the sidebar, and modifications to CSS styles for better visual consistency.

Detailed summary

• Added Untitled.md to .gitignore.
• Updated sidebar in zhCN.ts to include a link for "常见问题".
• Increased font-weight in custom.css from 100 to 300 and added 500 for blockquote:hover.
• Revised content in index.md for clearer instructions on downloading and using LauncherX.
• Introduced a new FAQ section in faq.md with troubleshooting steps and solutions for common issues.

✨ Ask PR-Codex anything about this PR by commenting with /codex {your question}