Run ESLint in CI

.forgejo/workflows/build.yaml

@@ -8,6 +8,8 @@ jobs:
         uses: actions/checkout@v4
       - name: Install dependencies
         run: npm install
+      - name: Run ESLint
+        run: npx eslint ./*.ts
       - name: Write signing key
         run: echo "$SIGNING_KEY" > key.pem
         env: