ci: add PR test + lint workflow

.github/workflows/ci.yml

@@ -0,0 +1,68 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+concurrency:
+  group: ci-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
+        with:
+          persist-credentials: false
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
+        with:
+          python-version: '3.13'
+      - run: python -m pip install --upgrade pip
+      - run: pip install -e ".[dev]"
+      - name: Ruff
+        run: ruff check .
+
+  test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ['3.10', '3.11', '3.12', '3.13']
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
+        with:
+          persist-credentials: false
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
+        with:
+          python-version: ${{ matrix.python-version }}
+      - run: python -m pip install --upgrade pip
+      # Install the framework extras so the adapter handler tests actually run
+      # (instead of skipping). langchain-core covers the LangChain handler tests.
+      - run: pip install -e ".[dev,langchain]"
+      - name: Pytest
+        run: pytest -q
+
+  test-bare:
+    # Locks the dependency-free contract: the package and its test suite must
+    # work with NO framework extra installed (handler tests skip cleanly, no
+    # import errors). This is what publish.yml runs before releasing.
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
+        with:
+          persist-credentials: false
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
+        with:
+          python-version: '3.13'
+      - run: python -m pip install --upgrade pip
+      - run: pip install -e ".[dev]"
+      - name: Pytest (no extras)
+        run: pytest -q