ci: Use codspeed for benchmarking

.github/workflows/codspeed.yml

@@ -0,0 +1,65 @@
+name: CodSpeed Benchmarks
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+    branches: ["main"]
+  merge_group:
+  workflow_dispatch:
+
+env:
+  CARGO_TERM_COLOR: always
+  RUST_BACKTRACE: 1
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref_name }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  benchmarks:
+    name: Run benchmarks
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          persist-credentials: false
+
+      - uses: ./.github/actions/rust
+        with:
+          version: stable
+          tools: cargo-codspeed
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - id: nss-version
+        run: echo "minimum=$(cat neqo-crypto/min_version.txt)" >> "$GITHUB_OUTPUT"
+
+      - uses: ./.github/actions/nss
+        with:
+          minimum-version: ${{ steps.nss-version.outputs.minimum }}
+
+      - run: |
+          for crate in $(cargo metadata --no-deps --format-version 1 | jq -r '.packages[].name'); do
+            if [ -e "$crate/benches" ]; then
+              for bench in "$crate/benches"/*.rs; do
+                bench=$(basename -s .rs "$bench")
+                # Set measurement mode from Cargo.toml metadata, default to "instrumentation".
+                mode=$(cargo metadata --no-deps --format-version 1 | jq -r --arg crate "$crate" --arg bench "$bench" '.packages[] | select(.name == $crate) | .metadata.bench[$bench].codspeed.mode // "instrumentation"')
+                echo "Building benchmark '$bench' in crate '$crate' with measurement mode '$mode'"
+                cargo codspeed build --package "$crate" --locked --features bench --bench "$bench" --release --measurement-mode "$mode"
+              done
+            fi
+          done
+
+      - name: Run the benchmarks
+        uses: CodSpeedHQ/action@4348f634fa7309fe23aac9502e88b999ec90a164 # v4.3.1
+        with:
+          mode: instrumentation
+          run: cargo codspeed run
+          token: ${{ secrets.CODSPEED_TOKEN }}