fix(redact): safely handle non-string inputs

redact_sensitive_text() now returns early for None and coerces other
non-string values to str before applying regex-based redaction,
preventing TypeErrors in logging/tool-output paths.

Cherry-picked from PR #2369 by aydnOktay.

tests/agent/test_redact.py

@@ -124,6 +124,13 @@ class TestPassthrough:
     def test_none_returns_none(self):
         assert redact_sensitive_text(None) is None
 
+    def test_non_string_input_int_coerced(self):
+        assert redact_sensitive_text(12345) == "12345"
+
+    def test_non_string_input_dict_coerced_and_redacted(self):
+        result = redact_sensitive_text({"token": "sk-proj-abc123def456ghi789jkl012"})
+        assert "abc123def456" not in result
+
     def test_normal_text_unchanged(self):
         text = "Hello world, this is a normal log message with no secrets."
         assert redact_sensitive_text(text) == text