test: isolate CLI output capture with monkeypatch/redirect to fix stdout corruption in full suite runs (Issue #178)

- Replace raw patch("sys.stdout") and contextlib.redirect_stderr with pytest MonkeyPatch or contextlib redirect scoped to main calls in CLI tests (create_*, prs, python_cli, manage_labels, merge_pr, review_pr).
- Add regression tests in test_review_proofs.py for stdout/stderr remaining usable.
- Ensures normal pytest summary output without junitxml workaround; improves review validation reporting per #173.
- No behavior change to production code or gates.

Refs #178

tests/test_migrate_profiles.py

@@ -9,6 +9,8 @@ import shutil
 from unittest.mock import patch
 from io import StringIO
 
+from _pytest.monkeypatch import MonkeyPatch
+
 # Add project root to sys.path
 PROJECT_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 if PROJECT_ROOT not in sys.path:
@@ -127,24 +129,29 @@ class TestMigrateProfiles(unittest.TestCase):
         v2_data = migrate_profiles.migrate_v1_to_v2(self.v1_content)
         self.assertTrue(migrate_profiles.validate_v2_data(v2_data))
 
-    @patch("sys.stdout", new_callable=StringIO)
-    def test_dry_run_default(self, mock_stdout):
+    def test_dry_run_default(self):
         """Verify that running without -w prints generated config without modifying files."""
-        output_file = os.path.join(self.temp_dir, "migrated_dry.json")
-        test_args = [
-            "migrate_profiles.py",
-            "-i", self.input_file,
-            "-o", output_file
-        ]
-        with patch.object(sys, "argv", test_args):
-            with self.assertRaises(SystemExit) as cm:
-                migrate_profiles.main()
-            self.assertEqual(cm.exception.code, 0)
+        monkeypatch = MonkeyPatch()
+        mock_stdout = StringIO()
+        monkeypatch.setattr(sys, "stdout", mock_stdout)
+        try:
+            output_file = os.path.join(self.temp_dir, "migrated_dry.json")
+            test_args = [
+                "migrate_profiles.py",
+                "-i", self.input_file,
+                "-o", output_file
+            ]
+            with patch.object(sys, "argv", test_args):
+                with self.assertRaises(SystemExit) as cm:
+                    migrate_profiles.main()
+                self.assertEqual(cm.exception.code, 0)
 
-        self.assertFalse(os.path.exists(output_file))
-        self.assertFalse(os.path.exists(f"{self.input_file}.bak"))
+            self.assertFalse(os.path.exists(output_file))
+            self.assertFalse(os.path.exists(f"{self.input_file}.bak"))
 
-        stdout_output = mock_stdout.getvalue()
+            stdout_output = mock_stdout.getvalue()
+        finally:
+            monkeypatch.undo()
         self.assertIn("DRY-RUN MODE", stdout_output)
         self.assertIn("version", stdout_output)
         self.assertIn("identities", stdout_output)
@@ -165,13 +172,18 @@ class TestMigrateProfiles(unittest.TestCase):
             json.dump(sensitive, f)
 
         test_args = ["migrate_profiles.py", "-i", self.input_file]
-        with patch("sys.stdout", new_callable=StringIO) as mock_stdout:
+        monkeypatch = MonkeyPatch()
+        mock_stdout = StringIO()
+        monkeypatch.setattr(sys, "stdout", mock_stdout)
+        try:
             with patch.object(sys, "argv", test_args):
                 with self.assertRaises(SystemExit) as cm:
                     migrate_profiles.main()
                 self.assertEqual(cm.exception.code, 0)
 
-        stdout_output = mock_stdout.getvalue()
+            stdout_output = mock_stdout.getvalue()
+        finally:
+            monkeypatch.undo()
         self.assertNotIn("super-secret-token-value", stdout_output)
         self.assertNotIn("token", stdout_output.lower())