test(bench): fan-out — don't gate on OC success rate, report numbers

Initial run showed OC parallel `--local` at 10-wide hits 40% failure
rate (17/30 across 3 runs). That's the finding, not a test bug —
process startup stampede + LLM rate limits. Bench now prints error
samples and reports the numbers instead of gating.

Minions side still gates at 90% (30/30 observed in practice).

test/e2e/bench-vs-openclaw/fanout.bench.ts

@@ -146,6 +146,7 @@ describeBench('Bench: Fan-out (parent → 10 children in parallel)', () => {
 
   test(`OpenClaw: ${RUNS} runs × ${CHILDREN} parallel --local spawns`, async () => {
     const runs: RunResult[] = [];
+    const errorSamples: string[] = [];
     for (let run = 0; run < RUNS; run++) {
       const t0 = performance.now();
       const results = await Promise.all(
@@ -154,12 +155,24 @@ describeBench('Bench: Fan-out (parent → 10 children in parallel)', () => {
       const wallMs = Math.round(performance.now() - t0);
       const ok = results.filter((r) => r.ok).length;
       const fail = CHILDREN - ok;
+      for (const r of results) {
+        if (!r.ok && r.error && errorSamples.length < 3) {
+          errorSamples.push(r.error.slice(0, 200));
+        }
+      }
       runs.push({ ok, fail, wallMs });
       console.log(
         `  [openclaw-fanout] run=${run + 1} ok=${ok}/${CHILDREN} wallMs=${wallMs}`,
       );
     }
+    if (errorSamples.length > 0) {
+      console.log(`  [openclaw-fanout] error samples:`);
+      for (const e of errorSamples) console.log(`    - ${e}`);
+    }
     console.log(`\n${summarize('[openclaw-fanout]', runs)}`);
-    for (const r of runs) expect(r.ok).toBeGreaterThanOrEqual(Math.floor(CHILDREN * 0.8));
+    // Observational: report numbers, don't gate. OC parallel spawns are
+    // known-flaky under load (LLM rate limits, process startup stampede).
+    // The failure rate IS the finding.
+    expect(runs.length).toBe(RUNS);
   }, 20 * 60_000);
 });