feat: configure Heatmap sample column

[phoman14]

Changes

• Add sample.name.column to heatmapSC() for selecting the metadata field used by sample.names filtering; it defaults to orig.ident.
• Preserve metadata names exactly and keep annotation selection independent of sample filtering.
• Add coverage for the default field, a custom punctuated sample column, and no metadata-name mutation.
• Update the Heatmap reference page and visualization vignette for the new sample column argument.

Issues

Addresses the beta-003 Heatmap metadata-column compatibility finding from the release tracking report.

PR Checklist

• This comment contains a description of changes with justifications, with any relevant issues linked.
• Write unit tests for any new features, bug fixes, or other code changes.
• Update the docs if there are any API changes (roxygen2 comments, vignettes, readme, etc.).
• Update NEWS.md with a short description of any user-facing changes and reference the PR number. Follow the style described in https://style.tidyverse.org/news.html
• Run devtools::check() locally and fix all notes, warnings, and errors.

Validation

• The local focused Heatmap suite passed with no failures, including visual snapshot assertions.
• The suite emitted 23 pre-existing namespace import masking warnings while loading SCWorkflow; no warnings came from Heatmap execution or snapshot comparisons.
• tools::checkRd("man/heatmapSC.Rd") passed after regenerating reference documentation.