Add CI workflow documentation

Documents the GitHub Actions test workflow setup, triggers, steps,
and troubleshooting guide for evaluomeR package testing.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: neobernad

.github/CI_WORKFLOW.md

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+# GitHub Actions CI Workflow
+
+This document describes the continuous integration (CI) workflow for the evaluomeR package.
+
+## Overview
+
+The `.github/workflows/test.yaml` workflow automatically runs your R package tests whenever code is pushed or a pull request is created. This ensures code quality and prevents regressions before merging to main branches.
+
+## Workflow Triggers
+
+The workflow runs on the following events:
+
+- **Push**: Any push to `main`, `master`, or `develop` branches
+- **Pull Request**: Any pull request targeting `main`, `master`, or `develop` branches
+- **Manual**: Manually triggered via GitHub Actions UI (workflow_dispatch)
+
+## Test Matrix
+
+Tests run across multiple R versions to ensure compatibility:
+
+- **R 4.3** - Latest stable release from that series
+- **Latest R** - Most current R version available
+
+All testing occurs on **Ubuntu Latest** runner.
+
+## Workflow Steps
+
+### 1. Checkout
+Clones your repository code.
+
+### 2. Set up R
+Installs the specified R version using the official r-lib setup action.
+
+### 3. Install System Dependencies
+Installs required system libraries:
+- `libcurl4-openssl-dev` - For HTTP communication
+- `libssl-dev` - For SSL/TLS support
+- `libxml2-dev` - For XML parsing
+
+### 4. Install R Dependencies
+Automatically installs all package dependencies declared in `DESCRIPTION`:
+- **Depends**: SummarizedExperiment, MultiAssayExperiment, dplyr, cluster, fpc, randomForest, flexmix, RSKC, sparcl
+- **Imports**: All packages listed in the Imports field
+- **Extra packages**: devtools (for package installation)
+
+### 5. Install Package
+Builds and installs your package locally using `devtools::install_local()`.
+
+### 6. Run Tests
+Executes all test scripts in the `tests/` directory matching the pattern `test*.R`:
+- testARI.R
+- testATSC.R
+- testATSC_GoldStandard.R
+- testATSC_parallel.R
+- testAll.R
+- testAlpha_parallel.R
+- testAnalysis.R
+- testCBI.R
+- testCH_index.R
+- testDataPreprocessing.R
+- testK_optimo_parallel.R
+- testL1_clustering.R
+- testMetricsRelevancy.R
+- testPCA.R
+- testQuality.R
+- testQuality_parallel.R
+- testStability.R
+- testStability_parallel.R
+
+Each test is sourced in sequence, with detailed output showing which test is running. If any test fails, the workflow exits with status 1 and reports the error.
+
+### 7. Upload Artifacts
+Test results and scripts are uploaded as workflow artifacts for 30 days, allowing you to review test output even after the workflow completes.
+
+## Viewing Results
+
+### On GitHub
+1. Navigate to your repository
+2. Click the **Actions** tab
+3. Click on the workflow run to see detailed output
+4. Expand any step to see its console output
+5. Download artifacts from the "Artifacts" section
+
+### Badges
+You can add a status badge to your README:
+
+```markdown
+[![R Package Tests](https://github.com/neobernad/evaluomeR/actions/workflows/test.yaml/badge.svg)](https://github.com/neobernad/evaluomeR/actions/workflows/test.yaml)
+```
+
+## Troubleshooting
+
+### Tests Fail in CI but Pass Locally
+- Ensure your local R version matches one of the CI versions (R 4.3 or latest)
+- Check for platform-specific issues (paths, environment variables)
+- Verify all dependencies are correctly listed in DESCRIPTION
+
+### Missing Dependencies
+- Add missing packages to DESCRIPTION under either `Depends` or `Imports`
+- For system packages, add them to the "Install system dependencies" step
+- Re-run the workflow after updating DESCRIPTION
+
+### Long Test Execution Times
+- Consider splitting large parallel tests into separate workflows if needed
+- Optimize test code to reduce runtime
+- Check if tests are downloading large data files
+
+## Future Enhancements
+
+Possible improvements to the CI workflow:
+
+1. **Code Coverage**: Add code coverage reports using `covr` package
+2. **R CMD Check**: Add `R CMD check` for comprehensive package validation
+3. **Platform Matrix**: Extend to include macOS and Windows runners
+4. **Documentation Builds**: Generate and validate vignettes/documentation
+5. **Performance Benchmarks**: Track test execution times over time
+
+## Related Files
+
+- `.github/workflows/test.yaml` - The main workflow definition
+- `DESCRIPTION` - Package metadata and dependencies
+- `tests/` - Directory containing all test scripts