feat(push): add JPush integration for offline message push

Add JPush (极光推送) integration to enable push notifications for offline users. This includes:
- New jpush client package with API for batch push notifications
- Configuration for jpush (enabled, app_key, master_secret, production mode)
- Updated push service to send messages via JPush when users are offline
- Added PushChatMessage method with do-not-disturb checking
- Integrated push service with chat service to notify offline users of new messages
- Updated deployment workflow with JPush and related environment variables

internal/model/device_token.go

@@ -24,7 +24,7 @@ type DeviceToken struct {
 	UserID     string     `gorm:"column:user_id;type:varchar(50);index;not null" json:"user_id"` // 用户ID (UUID格式)
 	DeviceID   string     `gorm:"type:varchar(100);not null" json:"device_id"`                   // 设备唯一标识
 	DeviceType DeviceType `gorm:"type:varchar(20);not null" json:"device_type"`                  // 设备类型
-	PushToken  string     `gorm:"type:varchar(256);not null" json:"push_token"`                  // 推送Token（FCM/APNs等）
+	PushToken  string     `gorm:"type:varchar(256)" json:"push_token,omitempty"`                 // 推送Token（JPush RegistrationID等，Web端可为空）
 	IsActive   bool       `gorm:"default:true" json:"is_active"`                                 // 是否活跃
 	DeviceName string     `gorm:"type:varchar(100)" json:"device_name,omitempty"`                // 设备名称（可选）
 

internal/model/push_record.go

@@ -16,6 +16,7 @@ const (
 	PushChannelFCM       PushChannel = "fcm"       // Firebase Cloud Messaging
 	PushChannelAPNs      PushChannel = "apns"      // Apple Push Notification service
 	PushChannelHuawei    PushChannel = "huawei"    // 华为推送
+	PushChannelJPush     PushChannel = "jpush"     // 极光推送
 )
 
 // PushStatus 推送状态