fix(ui): also resync an open game on a foreground regain without a stream drop

Closes the residual tail of the previous commit: when the live stream stays
alive across a brief suspend (Telegram/iOS can pause the socket without tearing
it down), an in-game event shed from a full hub buffer is never recovered by
the reconnect refetch (no reconnect) or the open-game poll (it only runs while
the stream is down). Mirror the lobby's focus re-poll: bump app.resync on a
foreground regain that did not drop the stream, and have Game.svelte refetch
the open game once per resync. Also rescues a missed move/game_over after a
suspend. Add a silent-join mock seam + an e2e isolating this path; extend the
ARCHITECTURE §10 fallback note.

ui/e2e/quickmatch.spec.ts

@@ -64,3 +64,15 @@ test('quick game: a stream reconnect recovers a join missed while it was down',
   await expect(page.getByText('Robo')).toBeVisible();
   await expect(page.getByText(/Searching for opponent/)).toHaveCount(0);
 });
+
+test('quick game: a foreground resync recovers a join shed while the stream stayed alive', async ({ page }) => {
+  await enterOpenGame(page);
+  // The opponent joins but the event is shed with the stream still alive (no reconnect, and the
+  // poll only runs while the stream is down): nothing has recovered yet.
+  await page.evaluate(() => (window as unknown as { __mock: { joinOpponentSilently(): void } }).__mock.joinOpponentSilently());
+  await expect(page.getByText(/Searching for opponent/)).toBeVisible();
+  // Returning to the foreground resyncs the open game (pageshow drives goForeground).
+  await page.evaluate(() => window.dispatchEvent(new Event('pageshow')));
+  await expect(page.getByText('Robo')).toBeVisible();
+  await expect(page.getByText(/Searching for opponent/)).toHaveCount(0);
+});