ci: gate PRs on fmt and clippy, add run concurrency groups

.github/workflows/rust.yml

@@ -9,6 +9,10 @@ on:
 permissions:
   contents: read
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ !startsWith(github.ref, 'refs/tags/') }}
+
 env:
   CARGO_TERM_COLOR: always
 
@@ -24,6 +28,29 @@ jobs:
     - name: Run tests
       run: cargo test --verbose
 
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+    - uses: dtolnay/rust-toolchain@6c977a6ca4077a0ceb28ffbe03f59d46e9ac8772 # v1
+      with:
+        toolchain: stable
+        components: clippy, rustfmt
+    - name: Cache Cargo
+      uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      with:
+        path: |
+          ~/.cargo/registry
+          ~/.cargo/git
+          target
+        key: linux-cargo-${{ hashFiles('Cargo.lock') }}
+        restore-keys: linux-cargo-
+    - name: Check formatting
+      run: cargo fmt --all -- --check
+    - name: Clippy
+      run: cargo clippy --all-targets -- -D warnings
+
   cargo-deny:
     runs-on: ubuntu-latest
     strategy: