feat: add integration smoke tests

CLI-level smoke tests using --yaml output against real Twitter API.
Default skipped via @pytest.mark.smoke marker + pyproject.toml addopts.
Run locally with: uv run pytest -m smoke -v

.github/workflows/ci.yml

@@ -9,6 +9,9 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.8", "3.10", "3.12"]
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -19,7 +22,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: "3.12"
+          python-version: ${{ matrix.python-version }}
 
       - name: Install dependencies
         run: uv sync --extra dev