test(e2e): wait for DB readiness before opening the downloads page

On slow CI runners (macOS) the renderer can query SQLite while the DB
worker is still creating tables, leaving the downloads page on its
skeleton state forever. Poll a playlist read until it succeeds before
navigating on a cold profile.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/electron-backend-e2e/src/downloads.e2e.ts

@@ -17,6 +17,34 @@ async function openDownloadsPage(page: Page): Promise<void> {
     await page.waitForURL(/\/workspace\/downloads(?:\?.*)?$/);
 }
 
+/**
+ * On a cold profile the renderer can query SQLite while the DB worker is
+ * still creating tables ("database is locked" / "no such table" on slow CI
+ * runners), which leaves the downloads page on its skeleton forever. Wait
+ * until a playlist read succeeds before navigating.
+ */
+async function waitForDatabaseReady(page: Page): Promise<void> {
+    await expect
+        .poll(
+            () =>
+                page.evaluate(async () => {
+                    const electron = window.electron;
+                    if (!electron) {
+                        return false;
+                    }
+                    try {
+                        await (electron.dbGetAppPlaylistMetas?.() ??
+                            electron.dbGetAppPlaylists?.());
+                        return true;
+                    } catch {
+                        return false;
+                    }
+                }),
+            { timeout: 30000 }
+        )
+        .toBe(true);
+}
+
 test.describe('Electron Downloads', () => {
     test('@downloads @electron shows the add-a-playlist empty state when no sources exist', async ({
         dataDir,
@@ -24,6 +52,7 @@ test.describe('Electron Downloads', () => {
         const app = await launchElectronApp(dataDir);
 
         try {
+            await waitForDatabaseReady(app.mainWindow);
             await openDownloadsPage(app.mainWindow);
 
             await expect(