fix: patch _REDACT_ENABLED in test fixture for module-level snapshot

The _REDACT_ENABLED constant is snapshotted at import time, so
monkeypatch.delenv() alone doesn't re-enable redaction during tests
when HERMES_REDACT_SECRETS=false is set in the host environment.

tests/agent/test_redact.py

@@ -12,6 +12,8 @@ from agent.redact import redact_sensitive_text, RedactingFormatter
 def _ensure_redaction_enabled(monkeypatch):
     """Ensure HERMES_REDACT_SECRETS is not disabled by prior test imports."""
     monkeypatch.delenv("HERMES_REDACT_SECRETS", raising=False)
+    # Also patch the module-level snapshot so it reflects the cleared env var
+    monkeypatch.setattr("agent.redact._REDACT_ENABLED", True)
 
 
 class TestKnownPrefixes: