perf: add benchmarks for sim_round

[Fraser999]

Description

• Adds Criterion benchmarks for sim_round() covering bundles (varying count, DB latency, concurrency, sender distribution), standalone transactions, complex bundle shapes (multi-tx, host txs), and failure paths (preflight and EVM revert).
• Introduces LatencyDb wrapper around the in-memory test DB that sleeps on every DatabaseRef read, simulating real RPC round-trip costs. TestDb is now CacheDB<LatencyDb>, mirroring the production CacheDB<AlloyDB> layering, with existing tests using the LatencyDb with latency disabled to match existing behaviour.
• Extends TestDbBuilder with with_contract() and with_latency() helpers.

Example benchmark output

The command:

cargo bench --bench sim

This was run on a Ryzen 9 7900X × 24, and ran for ~11m 15s:

sim_varying_simple_bundle_counts_no_db_latency/bundle_count/1
                        time:   [234.55 µs 235.87 µs 236.86 µs]
sim_varying_simple_bundle_counts_no_db_latency/bundle_count/10
                        time:   [3.2674 ms 3.2835 ms 3.3035 ms]
Found 1 outliers among 10 measurements (10.00%)
  1 (10.00%) high mild
sim_varying_simple_bundle_counts_no_db_latency/bundle_count/100
                        time:   [33.786 ms 33.863 ms 33.987 ms]
sim_varying_simple_bundle_counts_no_db_latency/bundle_count/1000
                        time:   [343.52 ms 345.19 ms 346.62 ms]
Found 1 outliers among 10 measurements (10.00%)
  1 (10.00%) low mild

sim_10_simple_bundles_varying_db_latency/latency/0ms
                        time:   [3.2407 ms 3.2535 ms 3.2647 ms]
Benchmarking sim_10_simple_bundles_varying_db_latency/latency/50ms: Warming up for 3.0000 s
Warning: Unable to complete 10 samples in 5.0s. You may wish to increase target time to 23.6s.
sim_10_simple_bundles_varying_db_latency/latency/50ms
                        time:   [2.3594 s 2.3597 s 2.3600 s]
Benchmarking sim_10_simple_bundles_varying_db_latency/latency/200ms: Warming up for 3.0000 s
Warning: Unable to complete 10 samples in 5.0s. You may wish to increase target time to 94.1s.
sim_10_simple_bundles_varying_db_latency/latency/200ms
                        time:   [9.4096 s 9.4099 s 9.4102 s]

sim_100_simple_bundles_no_db_latency_varying_concurrency/thread_count/1
                        time:   [25.504 ms 25.540 ms 25.563 ms]
sim_100_simple_bundles_no_db_latency_varying_concurrency/thread_count/2
                        time:   [28.179 ms 28.720 ms 29.240 ms]
Found 2 outliers among 10 measurements (20.00%)
  2 (20.00%) high severe
sim_100_simple_bundles_no_db_latency_varying_concurrency/thread_count/4
                        time:   [33.793 ms 33.951 ms 34.096 ms]
Found 1 outliers among 10 measurements (10.00%)
  1 (10.00%) high mild
sim_100_simple_bundles_no_db_latency_varying_concurrency/thread_count/8
                        time:   [45.229 ms 45.770 ms 46.057 ms]
sim_100_simple_bundles_no_db_latency_varying_concurrency/thread_count/16
                        time:   [77.430 ms 77.688 ms 78.221 ms]
Found 1 outliers among 10 measurements (10.00%)
  1 (10.00%) high mild

sim_100_simple_bundles_no_db_latency_varying_sender_count/sender_count/1
                        time:   [25.908 ms 26.031 ms 26.129 ms]
sim_100_simple_bundles_no_db_latency_varying_sender_count/sender_count/5
                        time:   [31.306 ms 31.576 ms 31.929 ms]
sim_100_simple_bundles_no_db_latency_varying_sender_count/sender_count/20
                        time:   [33.422 ms 33.503 ms 33.601 ms]
sim_100_simple_bundles_no_db_latency_varying_sender_count/sender_count/100
                        time:   [34.148 ms 34.665 ms 35.716 ms]
Found 1 outliers among 10 measurements (10.00%)
  1 (10.00%) high severe

sim_100_bundles_no_db_latency_varying_txs_per_bundle/txs_per_bundle/1
                        time:   [33.863 ms 34.031 ms 34.157 ms]
sim_100_bundles_no_db_latency_varying_txs_per_bundle/txs_per_bundle/3
                        time:   [63.696 ms 63.886 ms 64.097 ms]
Found 2 outliers among 10 measurements (20.00%)
  2 (20.00%) high mild
Benchmarking sim_100_bundles_no_db_latency_varying_txs_per_bundle/txs_per_bundle/5: Warming up for 3.0000 s
Warning: Unable to complete 10 samples in 5.0s. You may wish to increase target time to 7.0s or enable flat sampling.
sim_100_bundles_no_db_latency_varying_txs_per_bundle/txs_per_bundle/5
                        time:   [92.419 ms 93.891 ms 95.434 ms]
Found 2 outliers among 10 measurements (20.00%)
  1 (10.00%) high mild
  1 (10.00%) high severe
sim_100_bundles_no_db_latency_varying_txs_per_bundle/txs_per_bundle/10
                        time:   [166.92 ms 168.18 ms 169.37 ms]

sim_100_bundles_no_db_latency_varying_host_txs_per_bundle/host_txs_per_bundle/0
                        time:   [33.835 ms 33.965 ms 34.063 ms]
Found 1 outliers among 10 measurements (10.00%)
  1 (10.00%) high mild
sim_100_bundles_no_db_latency_varying_host_txs_per_bundle/host_txs_per_bundle/1
                        time:   [21.841 µs 23.201 µs 25.496 µs]
sim_100_bundles_no_db_latency_varying_host_txs_per_bundle/host_txs_per_bundle/3
                        time:   [22.594 µs 24.331 µs 25.891 µs]
sim_100_bundles_no_db_latency_varying_host_txs_per_bundle/host_txs_per_bundle/5
                        time:   [25.124 µs 27.394 µs 29.828 µs]

sim_varying_tx_counts_with_no_db_latency/tx_count/1
                        time:   [265.82 µs 266.57 µs 267.39 µs]
sim_varying_tx_counts_with_no_db_latency/tx_count/10
                        time:   [3.5487 ms 3.5803 ms 3.6148 ms]
sim_varying_tx_counts_with_no_db_latency/tx_count/100
                        time:   [36.645 ms 36.836 ms 37.062 ms]
Found 1 outliers among 10 measurements (10.00%)
  1 (10.00%) high mild
sim_varying_tx_counts_with_no_db_latency/tx_count/1000
                        time:   [385.71 ms 388.59 ms 390.86 ms]
Found 1 outliers among 10 measurements (10.00%)
  1 (10.00%) low mild

sim_10_txs_with_varying_db_latency/latency/0ms
                        time:   [13.908 ms 15.909 ms 17.080 ms]
Benchmarking sim_10_txs_with_varying_db_latency/latency/50ms: Warming up for 3.0000 s
Warning: Unable to complete 10 samples in 5.0s. You may wish to increase target time to 23.9s.
sim_10_txs_with_varying_db_latency/latency/50ms
                        time:   [2.3710 s 2.3771 s 2.3831 s]
Found 3 outliers among 10 measurements (30.00%)
  2 (20.00%) low mild
  1 (10.00%) high mild
Benchmarking sim_10_txs_with_varying_db_latency/latency/200ms: Warming up for 3.0000 s
Warning: Unable to complete 10 samples in 5.0s. You may wish to increase target time to 94.4s.
sim_10_txs_with_varying_db_latency/latency/200ms
                        time:   [9.4087 s 9.4115 s 9.4164 s]
Found 2 outliers among 10 measurements (20.00%)
  1 (10.00%) high mild
  1 (10.00%) high severe

sim_10_simple_bundles_all_failing_preflight/latency/0ms
                        time:   [2.2787 µs 2.3106 µs 2.3489 µs]
Benchmarking sim_10_simple_bundles_all_failing_preflight/latency/50ms: Warming up for 3.0000 s
Warning: Unable to complete 10 samples in 5.0s. You may wish to increase target time to 5.0s.
sim_10_simple_bundles_all_failing_preflight/latency/50ms
                        time:   [500.62 ms 500.66 ms 500.73 ms]
Found 1 outliers among 10 measurements (10.00%)
  1 (10.00%) high severe
Benchmarking sim_10_simple_bundles_all_failing_preflight/latency/200ms: Warming up for 3.0000 s
Warning: Unable to complete 10 samples in 5.0s. You may wish to increase target time to 20.0s.
sim_10_simple_bundles_all_failing_preflight/latency/200ms
                        time:   [2.0006 s 2.0007 s 2.0007 s]

sim_10_simple_bundles_all_failing_execution/latency/0ms
                        time:   [343.26 µs 346.63 µs 350.19 µs]
sim_10_simple_bundles_all_failing_execution/latency/50ms
                        time:   [401.17 ms 401.22 ms 401.27 ms]
Found 1 outliers among 10 measurements (10.00%)
  1 (10.00%) high mild
Benchmarking sim_10_simple_bundles_all_failing_execution/latency/200ms: Warming up for 3.0000 s
Warning: Unable to complete 10 samples in 5.0s. You may wish to increase target time to 16.0s.
sim_10_simple_bundles_all_failing_execution/latency/200ms
                        time:   [1.6012 s 1.6013 s 1.6015 s]
Found 2 outliers among 10 measurements (20.00%)
  2 (20.00%) high mild

Related Issue

Closes ENG-1956.

Testing

• make fmt passes
• make clippy passes
• make test passes
• New tests added (if applicable)

[Fraser999]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• perf: add benchmarks for sim_round #242 👈 (View in Graphite)
• tests: add load tests to the cache ingestion and simulation loop #236
• tests: adds builder simulation test harness #219
• chore: adds claude setup #218
• main

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