Create CI build script

.github/workflows/build.yml

@@ -0,0 +1,26 @@
+name: Build
+run-name: Build
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+on:
+  - push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+      - name: Download cosmopolitan
+        uses: bjia56/setup-cosmocc@main
+        with:
+          version: "3.9.6"
+      - name: Build
+        run: ./build
+      - name: Upload artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: Executables
+          path: bin/*