refactor(jpush): move vendor field handling into ThirdPartyChannel struct

Move the vendor switch logic into the ThirdPartyChannel struct as Set/IsEmpty/Normalize
methods to improve encapsulation and eliminate code duplication in the vendor params
builder. Also simplify messageToParams to reuse buildMessagePayload results and remove
unused notification_type extras from push notifications.

internal/pkg/jpush/client.go

@@ -78,6 +78,42 @@ type ThirdPartyChannel struct {
 	Honor  map[string]any `json:"honor,omitempty"`
 }
 
+// Set 按厂商标识写入对应厂商的私有字段
+// vendor 对应 third_party_channel 的 key（xiaomi/huawei/oppo/vivo/meizu/fcm/honor）
+// 未知厂商将被忽略
+func (t *ThirdPartyChannel) Set(vendor string, m map[string]any) {
+	switch vendor {
+	case "xiaomi":
+		t.Xiaomi = m
+	case "huawei":
+		t.Huawei = m
+	case "oppo":
+		t.OPPO = m
+	case "vivo":
+		t.VIVO = m
+	case "meizu":
+		t.Meizu = m
+	case "fcm":
+		t.FCM = m
+	case "honor":
+		t.Honor = m
+	}
+}
+
+// IsEmpty 判断是否所有厂商字段均为空
+func (t *ThirdPartyChannel) IsEmpty() bool {
+	return t.Xiaomi == nil && t.Huawei == nil && t.OPPO == nil &&
+		t.VIVO == nil && t.Meizu == nil && t.Honor == nil && t.FCM == nil
+}
+
+// Normalize 当所有厂商字段为空时返回 nil，避免序列化出空的 third_party_channel 对象
+func (t *ThirdPartyChannel) Normalize() *ThirdPartyChannel {
+	if t == nil || t.IsEmpty() {
+		return nil
+	}
+	return t
+}
+
 type AndroidNotif struct {
 	Alert       string         `json:"alert"`
 	Title       string         `json:"title,omitempty"`