feat: add GitHub Actions workflow for running tests and uploading coverage.

Author: NullPointerDepressiveDisorder

.github/workflows/coverage.yml

@@ -0,0 +1,31 @@
+name: Run tests and upload coverage
+
+on: push
+
+jobs:
+    test:
+        name: Run tests and collect coverage
+        runs-on: ubuntu-latest
+        steps:
+            - name: Checkout code
+              uses: actions/checkout@v4
+              with:
+                  fetch-depth: 2
+
+            - name: Set up Python
+              uses: actions/setup-python@v6
+              with:
+                  python-version: "3.13"
+                  cache: "uv"
+
+            - name: Install dependencies
+              run: uv pip install -e .[dev]
+
+            - name: Run tests with coverage
+              run: uv run pytest --cov --cov-branch --cov-report=xml
+
+            - name: Upload coverage to Codecov
+              uses: codecov/codecov-action@v5
+              with:
+                  token: ${{ secrets.CODECOV_TOKEN }}
+                  slug: ${{ github.repository }}