fix(ci): inject API credentials in docker job before image build

.github/workflows/ui.yml

@@ -83,6 +83,11 @@ jobs:
             echo "extra=${IMAGE_LC}:branch-${SAFE}" >> $GITHUB_OUTPUT
           fi
 
+      - name: Inject API credentials
+        run: |
+          sed -i "s/__API_USERNAME__/${{ secrets.API_USERNAME }}/g" ui/src/environments/environment.prod.ts
+          sed -i "s/__API_PASSWORD__/${{ secrets.API_PASSWORD }}/g" ui/src/environments/environment.prod.ts
+
       - name: Login to GHCR
         uses: docker/login-action@v3
         with: