Add simple CI build flow for push requests

.github/workflows/build.yml

@@ -0,0 +1,50 @@
+name: "Build"
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: Build ${{ matrix.board }}
+    strategy:
+      fail-fast: false
+      matrix:
+        board: [weact_studio_rp2040_16mb]
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          submodules: 'recursive'
+
+      - name: Install dependencies
+        run: |
+          sudo apt update
+          sudo apt install -y cmake gcc-arm-none-eabi libnewlib-arm-none-eabi libstdc++-arm-none-eabi-newlib
+
+      - name: Clone and build pico-sdk
+        run: |
+          git clone https://github.com/raspberrypi/pico-sdk
+          cd pico-sdk
+          git checkout tags/2.1.1
+          git submodule update --init
+          cd ..
+
+      - name: Build firmware
+        env:
+          PICO_SDK_PATH: ${{ github.workspace }}/pico-sdk
+        run: |
+          mkdir -p build_ci
+          cd build_ci
+          cmake .. -DPICO_BOARD=${{ matrix.board }}
+          make -j$(nproc)
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: pico_fido2_${{ matrix.board }}
+          path: build_ci/pico_fido2.uf2