ci(github): 添加 GitHub Actions 工作流

- 在 push/PR 时自动编译和运行测试
- 安装 Ubuntu 依赖：liburing-dev libz-dev libbrotli-dev libssl-dev libnghttp2-dev
- 构建 coco submodule、编译 cocoon、运行单元测试和集成测试
- 可选运行性能基准（wrk）

.github/workflows/ci.yml

@@ -0,0 +1,48 @@
+name: CI
+
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+    branches: [main, master]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y \
+            build-essential cmake \
+            liburing-dev libz-dev \
+            libbrotli-dev libssl-dev \
+            libnghttp2-dev
+
+      - name: Build coco
+        run: |
+          cd coco
+          mkdir -p build && cd build
+          cmake ..
+          make -j$(nproc)
+
+      - name: Build cocoon
+        run: make
+
+      - name: Run unit tests
+        run: make unit-test
+
+      - name: Run integration tests
+        run: make test
+
+      - name: Run benchmark
+        run: |
+          # 安装 wrk
+          sudo apt-get install -y wrk || true
+          make bench || true