Merge branch 'maint'

# Conflicts:
#	src/bin/fips.rs
#	src/bin/fipstop/app.rs
#	src/config/mod.rs
#	src/config/node.rs
#	src/config/transport.rs
#	src/mmp/receiver.rs
#	src/mmp/sender.rs
#	src/node/handlers/handshake.rs
#	src/node/handlers/rekey.rs
#	src/node/lifecycle.rs
#	src/node/mod.rs
#	src/transport/ethernet/socket.rs
#	src/transport/mod.rs
#	src/upper/tun.rs

.github/workflows/ci.yml

@@ -26,6 +26,16 @@ env:
 # Builds on Linux x86_64, Linux aarch64, and macOS.
 # ─────────────────────────────────────────────────────────────────────────────
 jobs:
+  fmt:
+    name: Format check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt
+      - run: cargo fmt --check
+
   build:
     name: Build (${{ matrix.os }})
     runs-on: ${{ matrix.os }}