fix(electron): show the main window once its document has loaded; enforce J1 IPC and mutation counters

Re-lands 4gray/iptvnator#1788 on master. #1788 merged into its stacked base
fix/dashboard-hero-skeleton-flicker after that base had already been
squash-merged as #1782, so none of its changes reached master. The diff is
identical to #1788's (commit 0daacb29e); it applied cleanly.

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

.github/workflows/ci.yml

@@ -324,8 +324,23 @@ jobs:
             # Electron dependency check, the xvfb run, the summary lookup and
             # the job-summary report; shared with performance-ratchet.yml.
             - name: Run the performance journeys
+              id: journeys
               uses: ./.github/actions/performance-journeys
 
+            # Only the J1 counters shown deterministic on this runner; the
+            # other journey measurements stay evidence (see Ratchet in
+            # docs/architecture/performance-journeys.md). Here and not in
+            # the composite action, so the weekly tightening still measures
+            # a run that would fail it.
+            - name: Check the J1 runtime counters against the baselines
+              env:
+                  SUMMARY: ${{ steps.journeys.outputs.summary }}
+              run: >-
+                  node tools/performance/check-journey-ratchet.mjs
+                  --summary "$SUMMARY"
+                  --only launch/renderer.ipcCallsToFirstCard
+                  --only launch/renderer.domMutationsToFirstCard
+
             - name: Upload journey summaries
               if: always()
               uses: actions/upload-artifact@v7