ci: add CI workflow for main, fix release pipeline ordering and node version

- Add ci.yml to build on every push to main (Node 22)
- Add job-level guard on release build job (startsWith refs/tags/v)
- Bump Node to 22 in release.yml to satisfy zotero-plugin-scaffold >=22.8.0
- Extract publish-release as a third job (needs: [build, update-rolling-release])
  so the versioned release and XPI are only published after the full pipeline succeeds

.gitea/workflows/ci.yml

@@ -0,0 +1,26 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+          cache: "npm"
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build
+        run: npm run build