Add TODO for module tags without metadata

[sapunyangkut]

What changed

• add a focused TODO above generated module tags when no metadata map is used
• render the placeholder tag as "$bam" so Nextflow interpolates the variable
• leave the existing metadata tag output unchanged

Fixes #2536.

Validation

• rendered nf_core/module-template/main.nf with Jinja2 for both branches:
  • has_meta=true: tag "$meta.id", no new TODO
  • has_meta=false: one TODO immediately before tag "$bam"
• .venv\Scripts\prek.exe run --config .pre-commit-config.yaml --files nf_core/module-template/main.nf
• git diff --check

tests/modules/test_create.py could not reach its assertions locally because all 12 tests require a Nextflow executable during shared setup, which is unavailable in this Windows environment. No test failure was caused by the rendered template.

PR checklist

• This comment contains a description of changes and the reason
• CHANGELOG.md is updated (left for the repository bot)

Automation disclosure

This small template change was prepared and tested with OpenAI Codex automation. It received advisory AI reviews from an independent local agent and ChatGPT Web; both returned approval. No human review is claimed.

[mashehu]

Hi, thanks for the contribution. Please join the github org via the slack channel so the CI runs for you.