Add CI workflow for branch builds

.forgejo/workflows/ci.yml

@@ -0,0 +1,19 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          token: ${{ github.token }}
+      - name: Install
+        run: npm ci
+      - name: Build
+        run: npm run build
+        env:
+          NEXT_TELEMETRY_DISABLED: 1