fix(config): add request_timeout_seconds and stale_timeout_seconds to provider _KNOWN_KEYS

Both keys are documented in cli-config.yaml.example and read at runtime by
hermes_cli/timeouts.py (get_provider_request_timeout and get_provider_stale_timeout),
but the provider-entry validator in config.py flagged them as unknown, producing
noisy warnings on every CLI invocation for users who followed the documented config.

Fixes #16779

tests/hermes_cli/test_provider_config_validation.py

@@ -82,7 +82,7 @@ class TestNormalizeCustomProviderEntry:
         """Unknown config keys should produce a warning."""
         entry = {
             "base_url": "https://api.example.com/v1",
-            "api_key": "sk-test-key",
+            "api_key": "***",
             "unknownField": "value",
             "anotherBad": 42,
         }
@@ -91,6 +91,19 @@ class TestNormalizeCustomProviderEntry:
         assert result is not None
         assert any("unknown config keys" in r.message.lower() for r in caplog.records)
 
+    def test_timeout_keys_not_flagged_unknown(self, caplog):
+        """request_timeout_seconds and stale_timeout_seconds should not produce warnings."""
+        entry = {
+            "base_url": "https://api.example.com/v1",
+            "api_key": "***",
+            "request_timeout_seconds": 300,
+            "stale_timeout_seconds": 900,
+        }
+        with caplog.at_level(logging.WARNING):
+            result = _normalize_custom_provider_entry(entry, provider_key="test")
+        assert result is not None
+        assert not any("unknown config keys" in r.message.lower() for r in caplog.records)
+
     def test_camel_case_warning_logged(self, caplog):
         """camelCase alias mapping should produce a warning."""
         entry = {