fix(trader): Correct leverage ratio in AI prompt (PR #318)

- Fix leverage config visibility issue
- Ensure all symbols' leverage info in prompt
- Prevent AI from using wrong leverage
- Add per-symbol leverage information to decision context

Source: https://github.com/NoFxAiOS/nofx/pull/318

decision/engine.go

@@ -123,13 +123,18 @@ func GetFullDecisionWithCustomPrompt(ctx *Context, mcpClient *mcp.Client, custom
 
 	// 4. 解析AI响应
 	decision, err := parseFullDecisionResponse(aiResponse, ctx.Account.TotalEquity, ctx.BTCETHLeverage, ctx.AltcoinLeverage)
+
+	// 无论是否有错误，都要保存 SystemPrompt 和 UserPrompt（用于调试和决策未执行后的问题定位）
+	if decision != nil {
+		decision.Timestamp = time.Now()
+		decision.SystemPrompt = systemPrompt // 保存系统prompt
+		decision.UserPrompt = userPrompt     // 保存输入prompt
+	}
+
 	if err != nil {
 		return decision, fmt.Errorf("解析AI响应失败: %w", err)
 	}
 
-	decision.Timestamp = time.Now()
-	decision.SystemPrompt = systemPrompt // 保存系统prompt
-	decision.UserPrompt = userPrompt     // 保存输入prompt
 	return decision, nil
 }
 
@@ -273,9 +278,10 @@ func buildSystemPrompt(accountEquity float64, btcEthLeverage, altcoinLeverage in
 	sb.WriteString("# 硬约束（风险控制）\n\n")
 	sb.WriteString("1. 风险回报比: 必须 ≥ 1:3（冒1%风险，赚3%+收益）\n")
 	sb.WriteString("2. 最多持仓: 3个币种（质量>数量）\n")
-	sb.WriteString(fmt.Sprintf("3. 单币仓位: 山寨%.0f-%.0f U(%dx杠杆) | BTC/ETH %.0f-%.0f U(%dx杠杆)\n",
-		accountEquity*0.8, accountEquity*1.5, altcoinLeverage, accountEquity*5, accountEquity*10, btcEthLeverage))
-	sb.WriteString("4. 保证金: 总使用率 ≤ 90%\n\n")
+	sb.WriteString(fmt.Sprintf("3. 单币仓位: 山寨%.0f-%.0f U | BTC/ETH %.0f-%.0f U\n",
+		accountEquity*0.8, accountEquity*1.5, accountEquity*5, accountEquity*10))
+	sb.WriteString(fmt.Sprintf("4. 杠杆限制: **山寨币最大%dx杠杆** | **BTC/ETH最大%dx杠杆** (⚠️ 严格执行，不可超过)\n", altcoinLeverage, btcEthLeverage))
+	sb.WriteString("5. 保证金: 总使用率 ≤ 90%\n\n")
 
 	// 3. 输出格式 - 动态生成（始终追加）
 	sb.WriteString("#输出格式\n\n")