ci: Implement build, test, and release workflows using GitHub Actions.

Author: skilledwolf

.github/workflows/build-and-test.yml

@@ -0,0 +1,34 @@
+name: build-and-test
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Build sdist and wheel
+        run: |
+          python -m pip install -U pip build
+          python -m build -s -w
+
+      - name: Install wheel and smoke-check metadata
+        run: |
+          python -m pip install dist/*.whl
+          python - << 'PY'
+          import importlib.metadata as md
+          print("quantumhall_matrixelements version:", md.version("quantumhall_matrixelements"))
+          PY
+

.github/workflows/release.yml

@@ -0,0 +1,45 @@
+name: release
+
+on:
+  push:
+    tags:
+      - "v*"
+  workflow_dispatch:
+
+jobs:
+  build-and-publish:
+    runs-on: ubuntu-latest
+    # 👇 This must match exactly the environment you configure on PyPI
+    environment: release
+    permissions:
+      contents: read
+      id-token: write
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Build sdist and wheel
+        run: |
+          python -m pip install -U pip build
+          python -m build -s -w
+
+      - name: Smoke-check package metadata
+        run: |
+          python -m pip install dist/*.whl
+          python - << 'PY'
+          import importlib.metadata as md
+          print("quantumhall_matrixelements version:", md.version("quantumhall_matrixelements"))
+          PY
+
+      # Only publish on tag refs like v0.1.0
+      - name: Publish to PyPI via OIDC (Trusted Publisher)
+        if: startsWith(github.ref, 'refs/tags/v')
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          packages-dir: dist/
+