feat: 新增路由配置、通知和公告功能，并初始化相关服务和仓库。

internal/models/announcement.go

@@ -0,0 +1,16 @@
+package models
+
+// Announcement represents a system-wide broadcast message
+type Announcement struct {
+	BaseModel
+	Title     string           `gorm:"size:200;not null" json:"title"`
+	Content   string           `gorm:"type:text;not null" json:"content"`
+	Type      NotificationType `gorm:"size:30;not null;default:'system'" json:"type"`
+	SentCount int              `gorm:"default:0" json:"sent_count"`
+	CreatedBy uint             `gorm:"not null" json:"created_by"`
+}
+
+// TableName specifies the table name for Announcement
+func (Announcement) TableName() string {
+	return "announcements"
+}