Add GitHub CI and fix clippy warnings

.github/workflows/ci.yaml

@@ -0,0 +1,89 @@
+name: CI
+on:
+  pull_request:
+  push:
+
+permissions:
+  contents: read
+
+env:
+  RUST_BACKTRACE: full
+  RUSTDOCFLAGS: -Dwarnings
+  RUSTFLAGS: -Dwarnings
+
+jobs:
+  style:
+    name: Code style
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Rust stable
+        run: |
+          rustup update --no-self-update stable
+          rustup default stable
+
+      - name: Cache dependencies
+        uses: Swatinem/rust-cache@v2
+
+      - name: Rustfmt
+        run: cargo fmt -- --check
+
+      - name: Clippy
+        run: cargo clippy --workspace --all-targets -- -D clippy::dbg_macro -D clippy::todo
+
+      - name: Rustdoc
+        run: cargo doc --workspace
+
+  test:
+    strategy:
+      matrix:
+        rust: [stable]
+    name: Test ${{ matrix.rust }}
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Rust ${{ matrix.rust }}
+        run: |
+          rustup update --no-self-update ${{ matrix.rust }}
+          rustup default ${{ matrix.rust }}
+
+      - name: Cache Dependencies
+        uses: Swatinem/rust-cache@v2
+
+      - name: Build
+        run: cargo build --workspace --all-targets
+
+      - name: Test
+        run: cargo test --workspace --all-targets -- --include-ignored
+
+  nix-flake:
+    name: Flake package
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install nix
+        uses: cachix/install-nix-action@v26
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Cache nix store
+        uses: DeterminateSystems/magic-nix-cache-action@b46e247b898aa56e6d2d2e728dc6df6c84fdb738
+        with:
+          # I do NOT consent to share build cache between FlakeHub.
+          # This should NOT be the default.
+          use-flakehub: false
+
+      - name: Flake check
+        run: nix flake check --no-update-lock-file --show-trace
+
+      - name: Flake build
+        run: nix build --no-update-lock-file --show-trace --print-build-logs