ENH: Add VariationalRegistration remote module CID blobs (19 files, 3.69 MiB)

Stages 19 binary blobs referenced by .cid key files in the ITKVariationalRegistration
remote module so ExternalData can resolve them against
ITKTestingData/CID/.

Every blob was verified before staging by re-hashing to its legacy
SHA-512 or MD5 key and by recomputing its CIDv1-raw (sha2-256)
identifier from file contents. Zero mismatches.

Source: local $ExternalData_OBJECT_STORES and ITKTestingData/MD5/ tree.
No network fetches required.

Assisted-by: Claude Code -- bulk copy + verification pipeline

Author: hjmjohnson