test(case): require baseline session cleanup per mos-1350 review

packages/cli/tests/case1-accept.test.mjs

@@ -374,6 +374,7 @@ for(const fault of ['inner','outer','overflow'])test(`row253 C4 P10 ${fault} rea
    const baselineStart=performance.now(),baseline=run(h);
    baselineSeconds=(performance.now()-baselineStart)/1000;
    assert.equal(baseline.status,0,baseline.out+baseline.err);
+   assert.deepEqual(await pollFixtureGone(files),[],'baseline leaves no session');
   }
   const capture=cleanupFixture(t,files);const stop=fixtureGuard(t,files,7000);
   if(fault==='inner')put(join(h.hc,'peer-hang'),'');