test(stalker): cover radio playback surviving a category switch in web E2E (#1522)

The E2E added in #1517 proved the ITV case only. Radio shares the live
layout and the same context-panel handler, and its inline audio player is
gated on the store selection just like the ITV player, so a regression in
`onStalkerCategoryClicked` would silence a station the user never switched
away from. The new scenario mirrors the ITV one: play a station, pick
another category, wait for the sidebar title to change, and assert the
audio player is still mounted.

Closes #1521

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

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

@@ -552,6 +552,44 @@ test('@stalker radio — stations use the inline audio player without EPG', asyn
     expect(epgRequests).toHaveLength(0);
 });
 
+test('@stalker radio playback survives a category switch', async ({ page }) => {
+    // Radio shares the ITV layout and the same context-panel handler that
+    // used to clear the selected item on every category click (#1517). The
+    // inline audio player is gated on that selection, so a category switch
+    // silenced the station the user never switched away from.
+    await addStalkerPortal(page);
+
+    await page.getByRole('link', { name: /radio/i }).click();
+    await page.waitForURL(/stalker.*radio/);
+
+    const categories = page.locator('.category-item');
+    await expect(categories.nth(2)).toBeVisible({ timeout: 10_000 });
+    await categories.nth(1).click();
+
+    const sidebar = page.locator('app-stalker-live-stream-layout .sidebar');
+    const sidebarTitle = sidebar.locator('.category-title');
+    const stations = page.locator('[data-test-id="channel-item"]');
+    await expect(stations.first()).toBeVisible({ timeout: 20_000 });
+    const firstCategoryTitle = (await sidebarTitle.textContent())?.trim() ?? '';
+    expect(firstCategoryTitle).not.toBe('');
+
+    await stations.first().click();
+    await expect(stations.first()).toHaveClass(/active/, { timeout: 20_000 });
+    const audioPlayer = page.locator('app-audio-player');
+    await expect(audioPlayer).toBeVisible({ timeout: 20_000 });
+
+    await categories.nth(2).click();
+
+    // The sidebar re-filters to the new category (proves the click landed and
+    // change detection ran)…
+    await expect(sidebarTitle).not.toHaveText(firstCategoryTitle, {
+        timeout: 20_000,
+    });
+    await expect(stations.first()).toBeVisible({ timeout: 20_000 });
+    // …while the station picked from the previous category keeps playing.
+    await expect(audioPlayer).toBeVisible();
+});
+
 test('@stalker PWA skips bulk EPG across channel switches', async ({
     page,
 }) => {