fix(copilot): address second CodeRabbit review cycle

- Fix docstring: default is True, not False (config_test.py)
- Redact exception message from stream-error log for consistency
  with upstream-error log (openrouter_compat_proxy.py)

autogpt_platform/backend/backend/copilot/config_test.py

@@ -131,7 +131,7 @@ class TestClaudeAgentUseCompatProxyEnvFallback:
     prefixed ``CHAT_CLAUDE_AGENT_USE_COMPAT_PROXY`` env var and the
     unprefixed ``CLAUDE_AGENT_USE_COMPAT_PROXY`` form.  Regression
     guard for the bool-default pitfall: the field has a non-None
-    default (``False``), so Pydantic passes the default into the
+    default (``True``), so Pydantic passes the default into the
     validator when no value is provided and a naive ``if v is None``
     check would never fire.
     """

autogpt_platform/backend/backend/copilot/sdk/openrouter_compat_proxy.py

@@ -463,7 +463,9 @@ class OpenRouterCompatProxy:
             raise
         except aiohttp.ClientError as e:
             stream_error = e
-            logger.warning("OpenRouter compat proxy stream interrupted: %s", e)
+            logger.warning(
+                "OpenRouter compat proxy stream interrupted: %s", type(e).__name__
+            )
         finally:
             if not cancelled:
                 upstream_response.release()