Add GitHub actions for continuous integration

.github/workflows/ci.yaml

@@ -0,0 +1,45 @@
+name: CI
+on:
+  push:
+    # paths:
+    #   - 'firmware/**'
+  pull_request:
+    # paths:
+    #   - 'firmware/**'
+
+env:
+  CARGO_TERM_COLOR: always
+defaults:
+  run:
+    working-directory: firmware
+
+jobs:
+  check:
+    name: Check
+    runs-on: ubuntu-latest
+    steps:
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: riscv32imc-unknown-none-elf
+          components: clippy, rust-src, rustfmt
+      - name: Check out repository
+        uses: actions/checkout@v4
+      - name: Check formatting
+        run: cargo fmt --all --check
+      - name: Clippy
+        run: cargo clippy --workspace --all-targets --all-features -- --deny warnings --allow deprecated
+
+  build:
+    name: Build
+    needs: [check]
+    runs-on: ubuntu-latest
+    steps:
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: riscv32imc-unknown-none-elf
+      - name: Check out repository
+        uses: actions/checkout@v4
+      - name: Build everything
+        run: cargo build --workspace --all-targets --release