ENH: Add GrowCut remote module CID blobs (8 files, 65.69 MiB)

Stages 8 binary blobs referenced by .cid key files in the ITKGrowCut
remote module so ExternalData can resolve them against
ITKTestingData/CID/. All blobs recovered from local caches, verified
via legacy SHA-512/MD5 + CIDv1-raw recomputation. No network fetches.

Unresolved: 7 CID(s) not available locally.

Assisted-by: Claude Code

Author: hjmjohnson