feat: implement runtime reply service and refactor related components

internal/ai/runtime/reply_eligibility.go

@@ -0,0 +1,30 @@
+package runtime
+
+import (
+	"cs-agent/internal/models"
+	"cs-agent/internal/pkg/enums"
+
+	"github.com/mlogclub/simple/common/strs"
+)
+
+type replyEligibility struct{}
+
+func newReplyEligibility() *replyEligibility {
+	return &replyEligibility{}
+}
+
+func (e *replyEligibility) CanReply(conversation models.Conversation, message models.Message, aiAgent models.AIAgent) bool {
+	if message.SenderType != enums.IMSenderTypeCustomer {
+		return false
+	}
+	if conversation.HandoffAt != nil || conversation.CurrentAssigneeID > 0 {
+		return false
+	}
+	if aiAgent.ServiceMode == enums.IMConversationServiceModeHumanOnly {
+		return false
+	}
+	if strs.IsBlank(message.Content) {
+		return false
+	}
+	return true
+}