docs: update README screenshots with backtest lab

- Rename img.png to backtest-lab.png
- Arrange 12 screenshots in 6 pairs (2 per row)
- Add Backtest Lab to Web Interface Features section

README.md

@@ -51,12 +51,10 @@ Join our Telegram developer community: **[NOFX Developer Community](https://t.me
 |:---:|:---:|
 | <img src="screenshots/config-ai-exchanges.png" width="400" alt="Config - AI Models & Exchanges"/> | <img src="screenshots/config-traders-list.png" width="400" alt="Config - Traders List"/> |
 
-### Competition Mode
-<p align="center">
-<img src="screenshots/competition-page.png" width="400" alt="Competition Page"/>
-</p>
-
-*Multi-AI leaderboard with real-time performance comparison*
+### Competition & Backtest
+| Competition Mode | Backtest Lab |
+|:---:|:---:|
+| <img src="screenshots/competition-page.png" width="400" alt="Competition Page"/> | <img src="screenshots/backtest-lab.png" width="400" alt="Backtest Lab"/> |
 
 ### Dashboard
 | Overview | Market Chart |
@@ -77,8 +75,6 @@ Join our Telegram developer community: **[NOFX Developer Community](https://t.me
 |:---:|:---:|
 | <img src="screenshots/debate-arena.png" width="400" alt="Debate Arena"/> | <img src="screenshots/debate-create.png" width="400" alt="Create Debate"/> |
 
-*Multiple AI models debate trading decisions with different roles (Bull, Bear, Analyst, Contrarian, Risk Manager)*
-
 ---
 
 ## Supported Exchanges
@@ -284,6 +280,14 @@ All configuration is done through the web interface - no JSON file editing requi
 - Multiple rounds of debate with consensus voting
 - Auto-execute consensus trades
 
+### Backtest Lab
+- 3-step wizard configuration (Model → Parameters → Confirm)
+- Real-time progress visualization with animated ring
+- Equity curve chart with trade markers
+- Trade timeline with card-style display
+- Performance metrics (Return, Max DD, Sharpe, Win Rate)
+- AI decision trail with Chain of Thought
+
 ---
 
 ## Common Issues