Add minimal CI GitHub action

.github/workflows/ci.yml

+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v5
+        with:
+          version: "0.5.30"
+
+      - name: Initialize environment
+        uses: actions/setup-node@v4
+        with:
+          node-version-file: package.json
+          cache: yarn
+          cache-dependency-path: yarn.lock
+      - name: Install node modules
+        run: npm install
+      - name: Type-checking
+        run: npm run ts