ci: add astro check, GHA workflow, and pre-commit hook

.github/workflows/ci.yml

@@ -0,0 +1,36 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches-ignore:
+      - main
+      - starlight
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    name: Type-check & build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - name: Set up Node.js
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
+        with:
+          node-version: 24
+          cache: npm
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Type-check (astro check)
+        run: npm run check
+
+      - name: Build
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: npm run build

.pre-commit-config.yaml

@@ -0,0 +1,9 @@
+repos:
+  - repo: local
+    hooks:
+      - id: astro-check
+        name: astro check
+        entry: npm run check
+        language: system
+        pass_filenames: false
+        types_or: [ts, astro, mdx, markdown]