ci: add CI workflow to run tests on all pushes and PRs

Tests previously only ran on main pushes inside deploy.yml. PRs and
feature branches had no test gate. This adds a dedicated ci.yml that
runs pytest on every push and pull request.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: baijum

.github/workflows/ci.yml

@@ -0,0 +1,23 @@
+name: CI
+on:
+  push:
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+          cache: 'pip'
+      - name: Run tests
+        run: |
+          pip install -r requirements.txt
+          pip install pytest
+          if python -m pytest --collect-only -q >/dev/null 2>&1; then
+            pytest --tb=short
+          else
+            echo "No tests found, skipping"
+          fi