feat: add environment variables for digest and VAPID keys in build workflow

.gitea/workflows/build.yaml

@@ -139,6 +139,9 @@ jobs:
             cat > .env << EOF
             SECRET_KEY=${{ secrets.SECRET_KEY }}
             REFRESH_TOKEN_EXPIRY_DAYS=1
+            DIGEST_TOKEN_SECRET=${{ secrets.DIGEST_TOKEN_SECRET }}
+            VAPID_PUBLIC_KEY=${{ secrets.VAPID_PUBLIC_KEY }}
+            VAPID_PRIVATE_KEY=${{ secrets.VAPID_PRIVATE_KEY }}
             EOF
 
             echo "SECRET_KEY is set: $(grep -q 'SECRET_KEY=' .env && echo YES || echo NO)"