chore: polish repo for public release

Add MIT LICENSE, fix README clone URL and add CI/license badges,
flesh out setup.py metadata, add a GitHub Actions test workflow,
and remove dead code left over from earlier iterations.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.github/workflows/tests.yml

@@ -0,0 +1,25 @@
+name: Tests
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["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 -r requirements.txt -r requirements-dev.txt
+      - name: Run tests
+        run: pytest -m "not integration"