Add REGENIE phenotype and covariate sidecars for plink_simulated

[lyh970817]

Summary

This PR adds three tiny plink_simulated_* sidecar files to data/genomics/homo_sapiens/popgen/ so REGENIE module tests can cover:

• quantitative phenotype input
• binary phenotype input in REGENIE-compatible 0/1 form
• explicit covariate input

The new files extend the existing plink_simulated cohort rather than introducing a second GWAS fixture set.

Files Added

• data/genomics/homo_sapiens/popgen/plink_simulated_quantitative_phenoname.phe
• data/genomics/homo_sapiens/popgen/plink_simulated_binary_phenoname.phe
• data/genomics/homo_sapiens/popgen/plink_simulated_covariates.txt

Rationale

nf-core/modules already reuses plink_simulated.{bed,bim,fam,pgen,pvar,psam} for GWAS/popgen tests, but the existing phenotype sidecars are not sufficient to exercise REGENIE's intended test matrix cleanly:

• the existing plink_simulated_phenoname.phe is a binary 1/2 phenotype file, not a continuous quantitative trait
• that existing file was only usable for the quantitative path via a --force-qt workaround
• REGENIE binary mode expects 0/1/NA, so a dedicated 0/1 binary sidecar is also needed
• there was no shared covariate sidecar for the same cohort

Adding small deterministic sidecars on top of the existing cohort keeps the dataset reusable and avoids duplicating genotype bundles.

Data Provenance

These files are deterministic sidecars derived from the sample identifiers in the existing plink_simulated dataset.

They are synthetic tabular fixtures only:

• no sensitive or controlled-access data
• no external downloads
• no new biological source material

Size

The added files are small:

• plink_simulated_quantitative_phenoname.phe: 4.5 KB
• plink_simulated_binary_phenoname.phe: 3.0 KB
• plink_simulated_covariates.txt: 7.4 KB

Total added footprint: about 15 KB.

Validation

These files were validated locally by pointing the companion nf-core/modules REGENIE tests at this branch and running:

NF_MODULES_TESTDATA_BASE_PATH='file:///.../test-datasets-work/data/' nf-test test modules/nf-core/regenie/step1/tests/main.nf.test   --profile singularity --updateSnapshot --verbose --stopOnFirstFailure

NF_MODULES_TESTDATA_BASE_PATH='file:///.../test-datasets-work/data/' nf-test test modules/nf-core/regenie/step2/tests/main.nf.test   --profile singularity --updateSnapshot --verbose --stopOnFirstFailure

Companion PR

This dataset PR is required by the companion nf-core/modules PR: nf-core/modules#10800

[dialvarezs]

LGTM!