ci: add pytest workflow and demo notebook smoke tests

Run locked uv sync and pytest on pull requests. Validate examples/demo.ipynb
structure and optional live smoke when HOTDATA_API_KEY is set.

Author: eddietejeda

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: CI
+
+on:
+  push:
+    branches: ["main", "master"]
+  pull_request:
+
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: Test (Python 3.12)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+
+      - uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v6
+        with:
+          enable-cache: true
+
+      - name: Set up Python
+        run: uv python install 3.12
+
+      - name: Install dependencies
+        run: uv sync --locked
+
+      - name: Test
+        run: uv run pytest -v