test: распознавать исполнившийся subtest в outcome (#550)

Issue: #550
User-Visible: no

scripts/mutation-guard-outcome.mjs

@@ -90,7 +90,7 @@ const ORACLE_SETUP_FAILURE = new RegExp([
 // Test frameworks include user/fixture text in failure diagnostics. A fixture
 // may literally mention ERR_MODULE_NOT_FOUND, so a proven assertion failure
 // must win over a setup-looking substring quoted inside that assertion.
-const ASSERTION_EVIDENCE = /(?:ERR_ASSERTION|AssertionError|^FAILED\s+\S+)/im;
+const ASSERTION_EVIDENCE = /(?:ERR_ASSERTION|AssertionError|^FAILED\s+\S+|^# Subtest:|^✖\s+)/im;
 
 export function classifyCommandResult(result, { phase = 'oracle', proof = MUTATION_PROOF.ASSERTION } = {}) {
   const stopped = interruption(result);

test/mutation-guard-outcome.test.mjs

@@ -61,6 +61,23 @@ test('#550 fixture: real named assertion failure is reusable proof', () => {
   });
   assert.equal(quotedFixture.kind, MUTATION_OUTCOME.ASSERTION_KILLED,
     'слово из fixture внутри AssertionError не маскирует реальное падение теста');
+  const runtimeEnoent = runGuardPhases('node --test ledger.test.mjs', {
+    execute: () => result(1, [
+      '# Subtest: ledger writes immediately',
+      'not ok 1 - ledger writes immediately',
+      "error: ENOENT: no such file or directory, open 'ledger.json'",
+    ].join('\n')),
+  });
+  assert.equal(runtimeEnoent.kind, MUTATION_OUTCOME.ASSERTION_KILLED,
+    'ошибка поведения внутри исполнившегося subtest не становится setup failure');
+  const specReporter = runGuardPhases('node --test ledger.test.mjs', {
+    execute: () => result(1, [
+      '✖ ledger writes immediately (2ms)',
+      "Error: ENOENT: no such file or directory, open 'ledger.json'",
+    ].join('\n')),
+  });
+  assert.equal(specReporter.kind, MUTATION_OUTCOME.ASSERTION_KILLED,
+    'node spec reporter также доказывает, что именованный test исполнился');
 });
 
 test('#550 fixture: green named assertion means the mutant survived', () => {