fix(ci): Add final bytecode cache clear after installations

The issue was timing - we were clearing cache before installations,
but uv sync/pip install were creating new .pyc files. This commit:

1. Adds PYTHONDONTWRITEBYTECODE=1 to prevent .pyc generation
2. Clears bytecode cache AFTER all installations complete
3. Ensures no stale .pyc files exist before tests run

For editable installs (-e .), Python loads from source directory,
so clearing cache after installation ensures the resolver sees the
latest method signatures with the authorization parameter.

.github/actions/setup-runner/action.yml

@@ -28,6 +28,7 @@ runs:
       shell: bash
       env:
         UV_EXTRA_INDEX_URL: ${{ steps.client-config.outputs.uv-extra-index-url }}
+        PYTHONDONTWRITEBYTECODE: 1
       run: |
         # Export UV env vars for current step and persist to GITHUB_ENV for subsequent steps
         if [ -n "$UV_EXTRA_INDEX_URL" ]; then
@@ -69,5 +70,9 @@ runs:
           uv pip install ${{ steps.client-config.outputs.install-source }}
         fi
 
+        echo "Final cleanup: removing all bytecode cache after installations"
+        find . -name "*.pyc" -type f -delete 2>/dev/null || true
+        find . -type d -name "__pycache__" -exec rm -rf {} + 2>/dev/null || true
+
         echo "Installed llama packages"
         uv pip list | grep llama