fix(upload): 分片上传 - 先预留配额并原子提交容量 (#679)

Co-authored-by: ddcat666 <26564566+ddcat666@users.noreply.github.com>

backend/internal/database/schema.go

@@ -17,6 +17,7 @@ import (
 func Models() []any {
 	return []any{
 		&model.CloudAgentExecution{},
+		&model.UploadReservation{},
 		&model.CloudAgentPiSession{},
 		&model.CloudAgentEventRecord{},
 		&model.CloudAgentMessageRecord{},