Per-computing-unit dataset mounting

[aicam]

Task Summary

Per-computing-unit dataset mounting — the platform step of the dataset-mounting feature (part of #6606), built on the mount infrastructure (#6862).

Let a user mount / list / unmount a dataset version on a running computing unit. The platform asks that CU's node mounter to perform the mount and reports the in-pod path back. Nothing consumes the mount yet — that is the follow-up Python-UDF task.

• Per-computing-unit mount API — GET/POST/DELETE /computing-unit/{cuid}/mounts (ComputingUnitManagingResource), backed by a credential-free MounterClient proxying to the CU's node mounter. Authorization stays in file-service via the pod's JWT.
• FileResolver — resolve a dataset path to (repo, versionHash) and back, so a mount is shown as /owner/dataset/version.
• "Mount datasets into computing unit" UI — a per-CU modal.

Task Type

• Other (feature implementation)