fix: close ungated CLI merge bypasses in review_pr.py and merge_pr.py (#16)

Reviewer found the MCP merge surface is gated but two local CLI scripts remain
ungated merge paths that LLM automations in this project have been using.
Close them (Option B — minimal safe fix; full gated CLI merge left to a
follow-up):

- review_pr.py: `--merge` now fails closed BEFORE any API call with a clear
  message directing callers to the gated `gitea_merge_pr` MCP workflow. The
  review-only path is unchanged. The merge execution block was removed.
- merge_pr.py: main() is now a fail-closed no-op — reads no credentials and
  makes no merge API call; prints that merge is only available via the gated
  workflow.
- README: the `review_pr.py` row and Quick Examples no longer advertise a CLI
  `--merge` path; added an audit-logging clarification that #16 returns
  structured gate/merge results but does not add durable audit logging, which
  is tracked by #18.

Tests updated/added:
- test_review_pr.py: `--merge` fails closed with no API call; message points to
  the gated workflow.
- test_merge_pr.py: merge fails closed with no API call, even with
  --force/--do/--title/--message; message points to the gated workflow.
- test_mcp_server.py: README no longer advertises the ungated CLI merge example.

The gated MCP `gitea_merge_pr` is unchanged and still gated; `gitea_review_pr`
still fails closed on merge=True; `gitea_submit_pr_review` still cannot merge.
No secrets, auth headers, raw env, or credential paths are exposed. No
Jenkins/Ops/GlitchTip/Release/deploy/CI behavior added. #17/#18 not started.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_merge_pr.py

@@ -15,49 +15,48 @@ FAKE_CREDS = "Basic dGVzdHVzZXI6dGVzdHBhc3M="
 
 class TestArgParsing(unittest.TestCase):
 
-    @patch("merge_pr.api_request")
-    @patch("merge_pr.get_auth_header", return_value=FAKE_CREDS)
-    def test_minimal_required_args(self, _auth, mock_api):
-        rc = merge_pr.main(["--pr-number", "81"])
-        self.assertEqual(rc, 0)
-        mock_api.assert_called_once()
-
     def test_missing_pr_number_exits(self):
         with self.assertRaises(SystemExit):
             merge_pr.main([])
 
 
-class TestAPIPayload(unittest.TestCase):
+class TestMergeDisabled(unittest.TestCase):
+    """Direct CLI merge is disabled (#16) — fails closed, no API call."""
 
     @patch("merge_pr.api_request")
     @patch("merge_pr.get_auth_header", return_value=FAKE_CREDS)
-    def test_payload_fields(self, _auth, mock_api):
+    def test_merge_fails_closed_without_api_call(self, _auth, mock_api):
+        rc = merge_pr.main(["--pr-number", "81"])
+        self.assertEqual(rc, 2)
+        mock_api.assert_not_called()
+
+    @patch("merge_pr.api_request")
+    @patch("merge_pr.get_auth_header", return_value=FAKE_CREDS)
+    def test_no_merge_even_with_force_and_method(self, _auth, mock_api):
         rc = merge_pr.main([
             "--pr-number", "81",
             "--do", "squash",
             "--title", "Squash title",
             "--message", "Squash message",
             "--force",
+            "--remote", "prgs",
         ])
-        self.assertEqual(rc, 0)
-        mock_api.assert_called_once()
-        method, url, auth, payload = mock_api.call_args[0]
-        self.assertEqual(method, "POST")
-        self.assertEqual(auth, FAKE_CREDS)
-        self.assertEqual(payload["Do"], "squash")
-        self.assertEqual(payload["MergeTitleField"], "Squash title")
-        self.assertEqual(payload["MergeMessageField"], "Squash message")
-        self.assertEqual(payload["force_merge"], True)
+        self.assertEqual(rc, 2)
+        mock_api.assert_not_called()
 
-    @patch("merge_pr.api_request")
-    @patch("merge_pr.get_auth_header", return_value=FAKE_CREDS)
-    def test_url_construction(self, _auth, mock_api):
-        merge_pr.main(["--pr-number", "81", "--remote", "prgs"])
-        url = mock_api.call_args[0][1]
-        self.assertEqual(
-            url,
-            "https://gitea.prgs.cc/api/v1/repos/Scaled-Tech-Consulting/Timesheet/pulls/81/merge"
-        )
+    def test_message_points_to_gated_workflow(self):
+        import io
+        import contextlib
+        with patch("merge_pr.get_auth_header", return_value=FAKE_CREDS), \
+                patch("merge_pr.api_request") as mock_api:
+            buf = io.StringIO()
+            with contextlib.redirect_stderr(buf):
+                rc = merge_pr.main(["--pr-number", "81"])
+        self.assertEqual(rc, 2)
+        mock_api.assert_not_called()
+        msg = buf.getvalue().lower()
+        self.assertIn("disabled", msg)
+        self.assertIn("gitea_merge_pr", msg)
 
 
 if __name__ == "__main__":