Add publish workflow

Author: synesthesiam

.github/workflows/publish.yml

@@ -0,0 +1,45 @@
+---
+name: Publish to PyPI
+
+on:
+  push:
+    tags:
+      - 'v*.*.*'   # e.g. v1.2.3
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+      - name: Install build tools
+        run: pip install build tomli
+      - name: Verify tag matches pyproject.toml version
+        run: |
+          TAG="${GITHUB_REF#refs/tags/v}"
+          FILE_VER=$(python -c "import tomli;print(tomli.load(open('pyproject.toml'))['project']['version'])")
+          [ "$TAG" = "$FILE_VER" ] || { echo "Tag $TAG != pyproject $FILE_VER"; exit 1; }
+      - name: Build dists
+        run: python -m build
+      - name: Upload artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: dist
+          path: dist/*
+
+  publish:
+    needs: build
+    runs-on: ubuntu-latest
+    environment: pypi
+    permissions:
+      id-token: write
+      contents: read
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          name: dist
+          path: dist
+      - name: Publish to PyPI via OIDC
+        uses: pypa/gh-action-pypi-publish@release/v1