fix(wechat): stop relay bootstrap from hijacking LLM provider selection.

Schedule LLM now binds an explicit provider key and fails closed on network errors so dead relay endpoints cannot block ordinary chat; relay bootstrap is opt-in only.

Co-authored-by: Cursor <cursoragent@cursor.com>

llm-providers.mjs

@@ -2304,9 +2304,6 @@ export function createLlmProviderService(
         relayProvider: RELAY_BOOTSTRAP.relayProvider,
       });
       if (!result.ok) return result;
-      if (result.key && !result.key.isSelected) {
-        await this.selectKey(result.key.id);
-      }
       return { ok: true, created: true, key: result.key };
     },
   };