ci: auto-build .deb and run tests on push/tag/PR

- test job: compile module + run 336 precision tests
- release job (on tag v*): build .deb, publish release with asset

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: peng.li24

.github/workflows/ci.yml

@@ -0,0 +1,50 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+    tags: ['v*']
+  pull_request:
+    branches: [master]
+
+jobs:
+  # ---- Test: build module + run 336 precision tests --------------------------
+  test:
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y python3 python3-pip python3-dev libeigen3-dev
+          pip3 install pybind11 numpy pytest
+
+      - name: Build test module
+        working-directory: tests
+        run: make
+
+      - name: Run tests
+        run: PYTHONPATH=tests:$PYTHONPATH python3 -m pytest tests/ -v
+
+  # ---- Release: build .deb and publish on tag -------------------------------
+  release:
+    if: startsWith(github.ref, 'refs/tags/v')
+    needs: test
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Build .deb
+        run: |
+          mkdir build && cd build
+          cmake .. -DCMAKE_BUILD_TYPE=Release
+          make deb
+
+      - name: Publish release
+        uses: softprops/action-gh-release@v2
+        with:
+          files: build/numpycpp-dev-*.deb
+          generate_release_notes: true
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}