test(web): follow master's icon-only add-provider button

The merge restored the icon variant of the Models add button; its
accessible name no longer carries the `+` text prefix.

apps/web/tests/models-settings.e2e.ts

@@ -58,7 +58,7 @@ describe('web e2e: Models settings page configures a dormant provider', () => {
     await dialog.getByText('填入各提供方的 API 密钥即可使用其模型。').waitFor({ timeout: 10_000 })
     // The dormant pi-ai adapter contributes its whole installed catalog; no
     // provider is configured yet, so the page is one add button.
-    const add = dialog.getByRole('button', { name: '+ 添加提供方' })
+    const add = dialog.getByRole('button', { name: '添加提供方' })
     await add.waitFor({ timeout: 10_000 })
     // The button enables once the dormant catalog lands in the join.
     await expect.poll(async () => add.isEnabled(), { timeout: 10_000 }).toBe(true)