fix: Install dev dependencies in GitHub Actions setup

The setup action was missing pytest, mypy, and other dev dependencies
needed for CI checks. Now installs all required tools for testing.

🤖 Generated with Claude Code
Co-Authored-By: Claude <noreply@anthropic.com>

Author: dugshub

.github/workflows/pattern-stack/setup/action.yml

@@ -21,5 +21,6 @@ runs:
     - name: Install dependencies
       shell: bash
       run: |
-        uv sync --frozen
+        uv sync --frozen --all-extras
+        uv pip install mypy pytest pytest-asyncio pytest-cov black ruff
         echo "✅ Pattern Stack environment ready (Python ${{ inputs.python-version }})"