ci: add pytest coverage and post as PR comment

Extends the pull request build to run pytest with coverage reporting.

Author: plexoos

.github/workflows/build-pull-request.yaml

@@ -32,8 +32,22 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install .
-          pip install mypy types-requests
+          pip install pytest pytest-cov mypy types-requests
 
-      - name: Type check with mypy
+      - name: Check types
         run: |
           mypy src
+
+      - name: Run tests
+        run: |
+          pytest -v --cov=src --cov-report=term-missing | tee coverage.txt
+          tail -n 10 coverage.txt > coverage_summary.txt
+
+      - name: Post test coverage as PR comment
+        if: matrix.python-version == '3.14'
+        run: |
+          body=$(printf "### Test Coverage Summary\n\`\`\`\n%s\n\`\`\`" "$(cat coverage_summary.txt)")
+          gh api repos/${{ github.repository }}/issues/${{ github.event.pull_request.number }}/comments \
+            -f body="$body"
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}