test(sim): WS-frame send→recv p99 assertion — the TCP_NODELAY tripwire (deploy-A §5.1)

Joins the CI-regressed sim-bench sweep (S7 style: threshold const with
budget+slack rationale, cfg(sim-bench) test, --test-threads=1 job).
Drives the real trunk WS route through the PRODUCTION serve path
(rutster::serve::serve_with_nodelay) over a real loopback socket at the
real 20ms cadence. Healthy ~1-2ms; a Nagle regression stalls ~40ms+;
threshold 20ms splits the regimes by an order of magnitude each way.
Verified load-bearing: fails when tcp_nodelay(false) — see module doc
for the Option D socket2 TCP_QUICKACK suppression that defeats the
Linux loopback's quick-ACK heuristic so the assertion actually
catches the Nagle regression on this runner.

Signed-off-by: Aaron D. Lee <himself@adlee.work>

Cargo.lock

@@ -1523,12 +1523,17 @@ dependencies = [
 name = "rutster-sim"
 version = "0.0.0"
 dependencies = [
+ "futures-util",
  "rutster",
+ "rutster-call-model",
  "rutster-media",
  "rutster-tap",
+ "rutster-trunk",
  "serde",
+ "socket2",
  "thiserror 1.0.69",
  "tokio",
+ "tokio-tungstenite",
  "toml",
  "tracing",
  "url",