feat: add realtime rate command

internal/module/rate/query.go

@@ -0,0 +1,28 @@
+package rate
+
+import (
+	"context"
+	"fmt"
+	"os/exec"
+	"strconv"
+	"strings"
+	"time"
+)
+
+func query(amount float64, base, quote string) (string, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 190*time.Second)
+	defer cancel()
+	cmd := exec.CommandContext(ctx, "python3", "scripts/rate_query.py", strconv.FormatFloat(amount, 'f', -1, 64), base, quote)
+	out, err := cmd.Output()
+	if ctx.Err() == context.DeadlineExceeded {
+		return "", fmt.Errorf("汇率服务超时，请稍后重试")
+	}
+	if err != nil {
+		return "", fmt.Errorf("汇率查询失败")
+	}
+	text := strings.TrimSpace(string(out))
+	if text == "" {
+		return "", fmt.Errorf("未获取到汇率")
+	}
+	return text, nil
+}