Add ldak/reml module

[lyh970817]

PR checklist

This PR adds the ldak/reml module — Run linkage disequilibrium-adjusted kinship (LDAK) restricted maximum likelihood (REML) heritability estimation on a precomputed genomic relationship matrix (GRM) and phenotype. It upstreams main.nf, meta.yml, environment.yml, and nf-test tests (including a stub), with topic-based version reporting, and snapshots the full output contract via sanitizeOutput. Tests reuse the existing public plink_simulated fixtures from nf-core/test-datasets; no new test data required.

Draft — stacked submission. This module's nf-test setup{} builds fixtures by running upstream LDAK modules, so this branch also includes its prerequisite module(s) — ldak/addgrms, ldak/calckins, ldak/createthinweights, ldak/filterrelatedness, ldak/thinpredictors — in the diff against master (stacked-by-inclusion). Those will drop out as their own PRs merge. Kept as a draft until the prerequisites land; only Docker has been run so far (Singularity/Conda to follow).

• This comment contains a description of changes (with reason).
• If you've fixed a bug or added code that should be tested, add tests!
• If you've added a new tool - have you followed the module conventions in the contribution docs
• If necessary, include test data in your PR (not necessary — reuses existing plink_simulated fixtures).
• Remove all TODO statements.
• Broadcast software version numbers to topic: versions - See version_topics
• Follow the naming conventions.
• Follow the parameters requirements.
• Follow the input/output options guidelines.
• Add a resource label
• Use BioConda and BioContainers if possible to fulfil software requirements.
• Ensure that the test works with either Docker / Singularity. Conda CI tests can be quite flaky:
  • For modules:
    • nf-core modules test ldak/reml --profile docker
    • nf-core modules test ldak/reml --profile singularity
    • nf-core modules test ldak/reml --profile conda