feat: add realtime rate command

internal/module/rate/module.go

@@ -0,0 +1,41 @@
+package rate
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"ops-assistant/internal/core/command"
+)
+
+type Module struct{}
+
+func New() *Module { return &Module{} }
+
+var re = regexp.MustCompile(`(?i)^/rate\s+([0-9]+(?:\.[0-9]+)?)\s*([a-z]{3})\s*(?:(?:to)\s*|->\s*|/\s*)([a-z]{3})\s*$`)
+
+func (m *Module) Handle(_ int64, cmd *command.ParsedCommand) (string, error) {
+	text := strings.TrimSpace(cmd.Raw)
+	if strings.EqualFold(text, "/rate") || strings.HasPrefix(strings.ToLower(text), "/rate help") {
+		return help(), nil
+	}
+	hit := re.FindStringSubmatch(text)
+	if hit == nil {
+		return help(), nil
+	}
+	amount, err := strconv.ParseFloat(hit[1], 64)
+	if err != nil || amount <= 0 {
+		return "❌ 金额无效", nil
+	}
+	base := strings.ToUpper(hit[2])
+	quote := strings.ToUpper(hit[3])
+	if base == quote {
+		return fmt.Sprintf("💱 %s → %s\n\n%s %s = %s %s", base, quote, hit[1], base, hit[1], quote), nil
+	}
+	return query(amount, base, quote)
+}
+
+func help() string {
+	return "💱 汇率转换\n\n用法：/rate 138sgd to cny\n\n也支持：\n/rate 100 usd to cny\n/rate 50 eur -> sgd\n/rate 1000 php/cny\n\n数据源：Google Finance、Visa、Mastercard。Visa/万事达为官方结算汇率；Google 为市场参考价。"
+}

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
+}