Add perf benches; flatten project structure

.github/workflows/benchmark.yml

@@ -0,0 +1,45 @@
+name: Benchmark
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+permissions:
+  contents: write
+  deployments: write
+
+jobs:
+  benchmark:
+    name: Run Criterion Benchmarks
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache dependencies
+        uses: Swatinem/rust-cache@v2
+
+      - name: Run benchmark
+        # We use --output-format bencher to make the output compatible with the
+        # github-action-benchmark action's 'cargo' tool parser.
+        run: cargo bench --bench bench_main --all-features -- --output-format bencher | tee output.txt
+
+      - name: Store benchmark result
+        uses: benchmark-action/github-action-benchmark@v1
+        with:
+          name: RulesXP Benchmark
+          tool: 'cargo'
+          output-file-path: output.txt
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          # Push and deploy GitHub pages branch automatically
+          auto-push: ${{ github.ref == 'refs/heads/main' }}
+          # Show alert with commit comment on detecting possible performance regression
+          alert-threshold: '125%'
+          comment-on-alert: ${{ github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository }}
+          fail-on-alert: true
+          alert-comment-cc-users: '@${{ github.actor }}'