fix(ci): write github packages auth to ~/.npmrc for yarn 1 classic

actions/setup-node writes auth via NPM_CONFIG_USERCONFIG which yarn 1
does not read. Explicitly append the auth token to ~/.npmrc so yarn can
find it when installing @staffbase/widget-sdk from npm.pkg.github.com.

Co-authored-by: GitHub Copilot <copilot@noreply.github.com>

Author: maximizeIT

.github/workflows/ci.yaml

@@ -27,6 +27,11 @@ jobs:
           registry-url: 'https://npm.pkg.github.com/'
           scope: '@staffbase'
 
+      - name: Configure GitHub Packages auth for yarn
+        run: echo "//npm.pkg.github.com/:_authToken=${NODE_AUTH_TOKEN}" >> ~/.npmrc
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.STAFFBOT_NPM_READ || secrets.GITHUB_TOKEN }}
+
       - name: Install Yarn Dependencies
         working-directory:  samples/weather-forecast
         run: yarn install --frozen-lockfile