add lint workflow

not sure that this works yet, we will see

.forgejo/workflows/lint.yml

@@ -0,0 +1,16 @@
+name: Lint
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  eslint:
+    runs-on: docker
+    steps:
+      - name: Checkout repository
+        uses: https://code.forgejo.org/actions/checkout@v4
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm run lint