feat(delivery): add delivery data models and auto-migration

Add 8 GORM models for MySQL one-click delivery: DeploymentTarget,
ResourceQuota, DeliveryTask, ResourceReservation, ResourceUsage,
MySQLInstance, ExecutionJob, TaskEvent. Register them in AutoMigrate.

Relates-to: #97

server/internal/database/database.go

@@ -23,5 +23,13 @@ func AutoMigrate(db *gorm.DB) error {
 		&model.Deployment{},
 		&model.DeploymentEvent{},
 		&model.AuditLog{},
+		&model.DeploymentTarget{},
+		&model.ResourceQuota{},
+		&model.DeliveryTask{},
+		&model.ResourceReservation{},
+		&model.MySQLInstance{},
+		&model.ResourceUsage{},
+		&model.ExecutionJob{},
+		&model.TaskEvent{},
 	)
 }