ci(perf): enforce J1 ipcCallsToFirstCard and domMutationsToFirstCard

With the main window shown at did-finish-load, J1 takes one path on the
runner: three dispatched runs (36928706097, 36928716010, 36928725392)
read 15 bridge calls and 559 DOM mutations in all 18 iterations,
stable: true. Both become baselines (slack 0), and the Performance
journeys job checks them with check-journey-ratchet.mjs --only.

The journeys document records the race, its cause, the before/after
wall-clock and which other J1 counters are now stable.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/electron-backend-e2e/src/window-visibility.e2e.ts

@@ -27,8 +27,9 @@ const setWindowState = (
     );
 
 /**
- * The app creates its window with `show: false` and shows it on
- * `ready-to-show`; a `hide()` sent earlier would be undone by that `show()`.
+ * The app creates its window with `show: false` and shows it at
+ * `ready-to-show` or `did-finish-load`, whichever comes first; a `hide()`
+ * sent earlier would be undone by that `show()`.
  */
 async function waitUntilShown(app: UnautomatedElectronApp): Promise<void> {
     await expect