test(browser): document blocked popup compatibility gates (#30537)

* test(browser): expose native popup admission blockers with faithful app events

* test(browser): probe Electron popup identity and inherited sandbox API limits

* test(browser): handle requests without associated contents in popup probe

* docs(browser): record blocked Electron popup compatibility gates and test routing

* docs(browser): keep popup evidence in PR

.github/workflows/pr.yml

@@ -1147,6 +1147,8 @@ jobs:
       # probe carries its own in-process deadline. Four at once on a 4-vCPU runner starve each other
       # past those deadlines; serial, every probe owns the runner.
       - name: Test Linux Electron lifecycle boundary
+        env:
+          ORCA_BACKGROUND_LAUNCH: '1'
         run: >-
           xvfb-run --auto-servernum pnpm exec vitest run --config config/vitest.config.ts
           --no-file-parallelism
@@ -1157,6 +1159,7 @@ jobs:
           src/main/browser/browser-route-dns-prefetch.electron.test.ts
           src/main/persistence/profile-state/profile-state-writer-stall.electron.test.ts
           src/main/browser/browser-popup-compatibility.electron.test.ts
+          src/main/browser/browser-popup-adapter-compatibility.electron.test.ts
           src/main/browser/browser-popup-native-compatibility.electron.test.ts
           src/main/browser/browser-popup-background-compatibility.electron.test.ts