Docs: Add screenshots section to all README files

Add professional UI screenshots to demonstrate the trading platform:
- Competition mode: Multi-AI leaderboard with real-time performance charts
- Trader details: Complete dashboard with equity curves and decision logs

Screenshots added to all language versions:
- README.md (English)
- README.zh-CN.md (Chinese)
- README.ru.md (Russian)
- README.uk.md (Ukrainian)

Images organized in screenshots/ directory with descriptive filenames:
- competition-page.png (AI battle interface)
- details-page.png (trader dashboard)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.zh-CN.md

@@ -78,6 +78,18 @@ NOFX现已支持**三大交易所**：Binance、Hyperliquid和Aster DEX！
 
 ---
 
+## 📸 系统截图
+
+### 🏆 竞赛模式 - AI实时对战
+![竞赛页面](screenshots/competition-page.png)
+*多AI排行榜和实时性能对比图表，展示Qwen vs DeepSeek实时交易对战*
+
+### 📊 交易详情 - 完整交易仪表盘
+![详情页面](screenshots/details-page.png)
+*专业交易界面，包含权益曲线、实时持仓、AI决策日志，支持展开查看输入提示词和AI思维链推理过程*
+
+---
+
 ## ✨ 核心特性
 
 ### 🏆 多AI竞赛模式