fix(auxiliary): pass base_url/api_key/api_mode through set_runtime_main for custom providers

When a user configures a custom: provider (e.g. custom:openclaw-router),
set_runtime_main() only stored provider and model in process-local globals.
_resolve_auto() then had no base_url or api_key for the custom endpoint,
causing Step 1 to fail and auxiliary tasks (approval, compression, title
generation) to fall through to the aggregator chain and route to wrong
providers.

Fix: extend set_runtime_main() to accept base_url, api_key, and api_mode
keyword arguments; store them in new globals alongside the existing provider
and model; fall back to these globals in _resolve_auto() when the main_runtime
dict is empty. The call site in conversation_loop.py now passes all five
fields from the agent object.

Fixes #34777

agent/conversation_loop.py

@@ -392,6 +392,9 @@ def run_conversation(
         set_runtime_main(
             getattr(agent, "provider", "") or "",
             getattr(agent, "model", "") or "",
+            base_url=getattr(agent, "base_url", "") or "",
+            api_key=getattr(agent, "api_key", "") or "",
+            api_mode=getattr(agent, "api_mode", "") or "",
         )
     except Exception:
         pass