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>

docs/architecture/validation-map.md

@@ -275,7 +275,10 @@ on `master`; before that, see the temporary-trigger note under Weekly
 tightening in the performance journeys document. `perf:journeys` builds the `electron-performance` configuration and runs every
 journey spec against the Xtream mock: J1 launch, then J2 open-source (a
 second set of launches, each followed by the click on the portal card), both
-written to the same summary file; its probe specs run with
+written to the same summary file. The `Performance journeys` job of `ci.yml`
+(warn-only) checks `renderer.ipcCallsToFirstCard` and
+`renderer.domMutationsToFirstCard` of that summary against the baselines;
+its probe specs run with
 `pnpm nx run electron-backend-e2e:test-performance-harness`, which CI runs in
 the `Unit Tests and Typechecks` job of `ci.yml` on every run. The
 `electron-backend-e2e` command targets call `tsx` and `playwright` directly,