[Feature] Add parallel plot utilities

[antoniojbt]

What was changed and why

• replace legacy parallel plotting script with exported epi_plot_parallel() and epi_plot_save_parallel()
• document new helpers and add foreach import
• cover parallel plotting with tests

Tests added

• tests/testthat/test-plot-parallel.R

Backward compatibility

• No breaking changes intended

Code coverage change

• No significant change reported

---

https://chatgpt.com/codex/tasks/task_e_68ade63b44b08326a8daa1ff1c75a828

[Copilot]

Pull Request Overview

This PR adds new parallel plotting utilities to replace legacy code with properly exported functions. The change transforms an internal script into two documented, tested functions for parallel plot generation and saving.

Key changes:

• Added epi_plot_parallel() and epi_plot_save_parallel() functions with full documentation
• Moved foreach from suggested to required dependencies
• Added comprehensive test coverage for parallel plotting functionality

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
R/epi_plot_parallel.R	New implementation of parallel plotting functions with proper error handling and documentation
tests/testthat/test-plot-parallel.R	Test suite covering both parallel plotting functions with multicore execution
man/epi_plot_parallel.Rd	Generated documentation for the new parallel plotting functions
legacy/epi_plot_en_masse.R	Removal of legacy parallel plotting script
NAMESPACE	Updated exports and imports including new foreach import
DESCRIPTION	Moved foreach from Suggests to Imports section

[codecov]

Codecov Report

❌ Patch coverage is 67.39130% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.54%. Comparing base (02d0a41) to head (e3075e6).

Files with missing lines	Patch %	Lines
R/epi_plot_parallel.R	67.39%	15 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #138      +/-   ##
==========================================
+ Coverage   84.82%   85.54%   +0.71%     
==========================================
  Files          61       62       +1     
  Lines        1351     1397      +46     
==========================================
+ Hits         1146     1195      +49     
+ Misses        205      202       -3     

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