ci: Add GitHub Actions for testing and publishing

- test.yml: Run tests on push/PR across Python 3.8-3.12 and all OS
- publish.yml: Auto-publish to PyPI when GitHub Release is created
- Uses PyPI trusted publishing (no token in secrets needed)

Author: tclark-ufl

.github/workflows/publish.yml

@@ -0,0 +1,48 @@
+# Publish to PyPI when a release is created
+name: Publish to PyPI
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    
+    # Required for trusted publishing (no token needed)
+    permissions:
+      id-token: write
+    
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+
+      - name: Install build dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install build twine
+
+      - name: Verify version matches tag
+        run: |
+          TAG_VERSION=${GITHUB_REF#refs/tags/v}
+          PKG_VERSION=$(python -c "import tomllib; print(tomllib.load(open('pyproject.toml', 'rb'))['project']['version'])")
+          if [ "$TAG_VERSION" != "$PKG_VERSION" ]; then
+            echo "Error: Tag version ($TAG_VERSION) doesn't match package version ($PKG_VERSION)"
+            exit 1
+          fi
+          echo "Version check passed: $PKG_VERSION"
+
+      - name: Build package
+        run: python -m build
+
+      - name: Check package
+        run: twine check dist/*
+
+      - name: Publish to PyPI
+        uses: pypa/gh-action-pypi-publish@release/v1
+        # Uses trusted publishing - configure at pypi.org/manage/project/dii-calculator/settings/publishing/
+

.github/workflows/test.yml

@@ -0,0 +1,40 @@
+# Run tests on every push and pull request
+name: Tests
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -e .[dev]
+
+      - name: Run tests
+        run: |
+          pytest tests/ -v --tb=short
+
+      - name: Test CLI
+        run: |
+          python -m dii --help
+          python -m dii --nutrients
+