ci: pass GITHUB_TOKEN to Composer to fix 504 rate-limit failures

Without authentication, Composer downloads from api.github.com hit
GitHub's unauthenticated rate limit, causing transient HTTP 504 errors
across all matrix app jobs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: matsaur

.github/workflows/static-code-analysis.yml

@@ -210,6 +210,8 @@ jobs:
       - name: Composer install
         working-directory: apps-external/${{ matrix.app }}
         run: composer install --no-interaction --prefer-dist
+        env:
+          COMPOSER_AUTH: '{"github-oauth":{"github.com":"${{ secrets.GITHUB_TOKEN }}"}}'
 
       - name: Locate psalm binary
         id: psalm-bin