fix: 移除lcfc案例，更新案例图片和映射

[hellozhangyan1221-crypto]

Summary

• 移除 lcfc（告别万行Excel）案例，因未获授权
• 从中/英/日三语文案中移除对应内容
• 更新 CaseStudies 组件和 assets 中的映射
• 替换案例4图片

Test plan

• 验证首页案例轮播正常显示4个案例
• 验证轮播切换、自动播放功能正常
• 验证移动端/桌面端布局正常

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[cla-assistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

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[github-actions]

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