fix: watchdog health check test expects 5 checks not 4 (#1512)

The test_returns_report_with_all_checks expected 4 checks but
run_health_checks() returns 5 (including Kimi Heartbeat).

Fixed:
- Updated docstring: "all four checks" → "all five checks"
- Updated assertion: len(report.checks) == 5
- Added "Kimi Heartbeat" to expected check names

Closes #1512

tests/test_nexus_watchdog.py

@@ -293,7 +293,7 @@ class TestHealthReport:
 
 class TestRunHealthChecks:
     def test_returns_report_with_all_checks(self, tmp_path):
-        """run_health_checks() returns a report with all four checks."""
+        """run_health_checks() returns a report with all five checks."""
         with patch("socket.socket") as mock_sock, \
              patch("subprocess.run") as mock_run:
             mock_sock.return_value.connect_ex.return_value = 0
@@ -303,9 +303,10 @@ class TestRunHealthChecks:
                 heartbeat_path=tmp_path / "missing.json",
             )
 
-        assert len(report.checks) == 4
+        assert len(report.checks) == 5
         check_names = {c.name for c in report.checks}
         assert "WebSocket Gateway" in check_names
         assert "Consciousness Loop" in check_names
         assert "Heartbeat" in check_names
         assert "Syntax Health" in check_names
+        assert "Kimi Heartbeat" in check_names