Add CI quality gate workflow

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  quality:
+    name: Typecheck, Test, Coverage
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Bun
+        uses: oven-sh/setup-bun@v2
+
+      - name: Install dependencies
+        run: bun install --frozen-lockfile
+
+      - name: Typecheck
+        run: bun run typecheck
+
+      - name: Test with coverage
+        run: bun test --coverage | tee coverage-summary.txt
+
+      - name: Upload coverage summary
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-summary
+          path: coverage-summary.txt