[GUI] Provider activation promise not awaited, may show stale state

[Vantalens]

File: packages/gui/src/App.tsx:510

Severity: Medium

Description:
activateProvider().then(onRefresh) chains but isn't awaited in onClick; if user rapidly clicks multiple providers, onRefresh fires before activations settle.

Code:

<Button onClick={() => client?.activateProvider(provider.id).then(onRefresh)}>激活</Button>

Failure Scenario:
User clicks Provider A → clicks Provider B immediately → both activations fire → onRefresh runs before backend processes them → UI shows wrong active provider.

Suggested Fix:
Disable button during activation or use async onClick handler.