Add CI workflow with linting, type checking, and tests

Set up GitHub Actions to run on pushes and PRs to master branch.
Uses pnpm for package management.

Author: pettinarip

.github/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 9
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'pnpm'
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Run linter
+        run: pnpm run lint
+
+      - name: Run type check
+        run: pnpm run type-check
+
+      - name: Run tests
+        run: pnpm test