refactor backend packages and global db service

backend/internal/models/project.go

@@ -0,0 +1,16 @@
+package models
+
+import "time"
+
+type SenlinAgentProject struct {
+	ID          uint   `gorm:"primaryKey"`
+	OwnerID     uint   `gorm:"index;not null"`
+	Name        string `gorm:"not null"`
+	Description string
+	CreatedAt   time.Time
+	UpdatedAt   time.Time
+}
+
+func (SenlinAgentProject) TableName() string {
+	return "senlin_agent_projects"
+}