fix(e2e): use mat-button-toggle value selectors for playlist type selection

mat-button-toggle elements inside a group render their internal buttons
with role="radio", not role="button", so getByRole('button') selectors
fail. Switch to attribute selectors targeting the value attribute instead.

https://claude.ai/code/session_01VU6ZZTG7YrhKhKBQvBfmpp

apps/web-e2e/src/xtream.e2e.ts

@@ -56,7 +56,7 @@ async function addXtreamPortal(
 
     await page.getByRole('button', { name: 'Add playlist' }).click();
     const dialog = page.locator('mat-dialog-container');
-    await dialog.getByRole('button', { name: 'Xtream' }).click();
+    await dialog.locator('mat-button-toggle[value="xtream"]').click();
 
     await dialog.locator('#title').fill(name);
     await dialog.locator('#serverUrl').fill(MOCK_SERVER);