Add the 0.4.2 backend release catalogs

[t-kalinowski]

Summary

• update the complete CUDA/RAPIDS backend catalog to the artifacts built from merge commit d427cd0
• refresh the CPU-only nvForest backend catalog from the same source for R 4.1 through R 4.6
• point both catalogs at the draft cuda-ml-backend-0.4.2 release

Public-facing changes

After the draft release is published, cuda_ml_install() can resolve backend revision 0.4.2 for every supported R minor. The complete backend contains the PCA and TSVD batch-dimension fix merged in PR #221. CPU-only nvForest installations resolve the corresponding 0.4.2 artifacts built from the same source commit.

The release remains a draft while this PR is open, so these catalog URLs are not yet available to unauthenticated package installations.

Internal changes

This PR changes only the two generated catalog TSV files. It does not change R code, native code, build tooling, or workflows.

Each catalog contains six rows covering R 4.1 through R 4.6. The rows record the generated filenames, 0.4.2 release URLs, byte sizes, archive SHA-256 values, and backend binary SHA-256 values. The package version remains 0.4.0 in artifact filenames because backend release revisions are versioned separately.

Validation

• backend workflow run 31018956949 passed all six R-version builds and the draft-release job at d427cd0
• the committed catalogs match the generated backend-lock artifact byte-for-byte
• Rscript -e 'devtools::test(filter = "runtime-loader", reporter = "summary")'
• git diff --check

Release sequencing

Keep cuda-ml-backend-0.4.2 as a draft until this PR merges. Publish the release after both catalogs are present on main.