chore(ci): add GitHub Actions workflow (#28)

.github/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Lint
+        run: |
+          pnpm --filter @multica/web lint
+          pnpm --filter @multica/desktop lint
+
+      - name: Type check
+        run: pnpm typecheck
+
+      - name: Build
+        run: pnpm build