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/basic.e2e.ts

@@ -12,7 +12,7 @@ test('basic test', async ({ page }) => {
     // Upload playlist test
     await page.getByRole('button', { name: 'Add playlist' }).click();
     const dialog = page.locator('mat-dialog-container');
-    await dialog.getByRole('button', { name: 'Add via file upload' }).click();
+    await dialog.locator('mat-button-toggle[value="file"]').click();
     await page.setInputFiles('input[type="file"]', fixturePath);
     await page.waitForURL(/\/workspace\/playlists\/.+\/all$/);
     await expect(page.getByText('test.m3u')).toBeVisible();