Refactor: Give AI full freedom to analyze raw sequence data

Remove prescriptive indicator combinations and let AI freely use all available data.
**Changes**:
- Emphasized AI has access to **raw sequence data** (MidPrices array, 4h candles)
- Listed all available sequences: price, technical (EMA/MACD/RSI), and capital flow (volume/OI)
- Removed hard-coded indicator combinations (e.g., "MACD + RSI + Volume")
- Changed from prescriptive examples to open-ended analysis freedom
- AI can now freely perform trend analysis, pattern recognition, support/resistance calculation
- Reduced minimum close-open interval from 30min to 15min for more flexibility
**Before**:
```
强信号示例:
- 趋势突破 + 多个指标确认（MACD + RSI + 成交量）
- 持仓量暴增 + 价格突破关键位
```
**After**:
```
你拥有的完整数据：
- 📊 原始序列：3分钟价格序列(MidPrices数组) + 4小时K线序列
- 📈 技术序列：EMA20序列、MACD序列、RSI7序列、RSI14序列
- 💰 资金序列：成交量序列、持仓量(OI)序列、资金费率
分析方法（完全由你自主决定）：
- 自由运用序列数据，你可以做趋势分析、形态识别、支撑阻力计算
- 多维度交叉验证（价格+量+OI+指标+序列形态）
- 用你认为最有效的方法发现高确定性机会
```
**Philosophy**: Trust AI to discover effective patterns in raw data rather than constraining it to pre-defined indicator combinations.
Co-Authored-By: tinkle-community <tinklefund@gmail.com>

decision/engine.go

@@ -244,17 +244,22 @@ func buildSystemPrompt(accountEquity float64) string {
 
 	// === 开仓信号强度 ===
 	sb.WriteString("# 🎯 开仓标准（严格）\n\n")
-	sb.WriteString("只在**强信号**时开仓，不确定就观望：\n\n")
-	sb.WriteString("**强信号示例**:\n")
-	sb.WriteString("- 趋势突破 + 多个指标确认（MACD + RSI + 成交量）\n")
-	sb.WriteString("- 持仓量暴增 + 价格突破关键位\n")
-	sb.WriteString("- 明确趋势 + 回调入场点\n")
-	sb.WriteString("- 信心度 ≥ 75\n\n")
-	sb.WriteString("**弱信号不开仓**:\n")
-	sb.WriteString("- 单一指标信号（仅RSI超卖）\n")
-	sb.WriteString("- 趋势不明确（横盘震荡）\n")
-	sb.WriteString("- 信心度 < 75\n")
-	sb.WriteString("- 刚平仓不久（<30分钟）就想再开\n\n")
+	sb.WriteString("只在**强信号**时开仓，不确定就观望。\n\n")
+	sb.WriteString("**你拥有的完整数据**：\n")
+	sb.WriteString("- 📊 **原始序列**：3分钟价格序列(MidPrices数组) + 4小时K线序列\n")
+	sb.WriteString("- 📈 **技术序列**：EMA20序列、MACD序列、RSI7序列、RSI14序列\n")
+	sb.WriteString("- 💰 **资金序列**：成交量序列、持仓量(OI)序列、资金费率\n")
+	sb.WriteString("- 🎯 **筛选标记**：AI500评分 / OI_Top排名（如果有标注）\n\n")
+	sb.WriteString("**分析方法**（完全由你自主决定）：\n")
+	sb.WriteString("- 自由运用序列数据，你可以做趋势分析、形态识别、支撑阻力计算\n")
+	sb.WriteString("- 多维度交叉验证（价格+量+OI+指标+序列形态）\n")
+	sb.WriteString("- 用你认为最有效的方法发现高确定性机会\n")
+	sb.WriteString("- 综合信心度 ≥ 75 才开仓\n\n")
+	sb.WriteString("**避免低质量信号**：\n")
+	sb.WriteString("- 单一维度（只看一个指标）\n")
+	sb.WriteString("- 相互矛盾（涨但量萎缩）\n")
+	sb.WriteString("- 横盘震荡\n")
+	sb.WriteString("- 刚平仓不久（<15分钟）\n\n")
 
 	// === 夏普比率自我进化 ===
 	sb.WriteString("# 🧬 夏普比率自我进化\n\n")