Add PR gate workflow (build, type-check, unit)

.github/workflows/build-unit-gate.yml

@@ -0,0 +1,43 @@
+name: Build & Unit Gate
+
+on:
+  pull_request:
+    branches: [master]
+  push:
+    branches: [master]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: pr-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  verify:
+    name: Build, type-check, unit
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - name: Checkout
+        uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5.0.1
+        with:
+          persist-credentials: false
+
+      - name: Set up Node
+        uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version: '22.19.0'
+          cache: npm
+
+      - name: Install
+        run: npm ci
+
+      - name: Build
+        run: npm run build
+
+      - name: Type-check
+        run: npm run check
+
+      - name: Unit gate
+        run: npm run test:unit