Plane: Cross-tenant asset authorization bypass in Plane Spaces public-board endpoints

Plane is an open-source project management tool. Prior to 1.4.0, Plane's dashboard asset endpoints in plane/app/views/asset/v2.py were remediated for two cross-tenant asset IDORs, CVE-2026-27705 and CVE-2026-46558. Those fixes added a membership check and project_id and workspace__slug scoping to the asset endpoints in that file. The Spaces app in plane/space/views/asset.py serves related public-board operations under /api/public/ but was not remediated. Its EntityAssetEndpoint and AssetRestoreEndpoint resolve a DeployBoard from a public anchor and then read or modify FileAsset rows scoped only to the board's workspace, without a membership check or project_id constraint. An attacker can therefore read, overwrite, or restore assets across projects and workspaces. This issue is fixed in 1.4.0.