fix: a slow answer to an approval still reaches the site (closes #540)

Chrome stopped the background worker about six minutes after a site's
request even with the approval window open, and the approval and the
site's waiting request went with it. Every approval is now added through
addPendingApproval(), which starts a timer in the worker that calls
runtime.getPlatformInfo() every 20 seconds while any approval is
pending; Chrome counts each call as activity.

tests/e2e/slowApproval.js, run by make test-e2e, leaves a transaction
and a signature approval open for seven minutes in minimized windows and
requires the site to receive both results. It drives Chromium over the
DevTools pipe because Playwright keeps DevTools attached to the worker.
Its loopback dApp server, shared with the Firefox suite, moves to
tests/e2e/dapp.js.

Model: opus-5-5

script/test-e2e

@@ -97,6 +97,18 @@ main() {
         -e HOME=/tmp \
         "$(cat "$IIDFILE")" \
         node tests/e2e/storagePartition.js
+
+    # Approvals left open for seven minutes in minimized windows, past the
+    # point where Chrome stopped the background worker when nothing kept it
+    # running. Its own program, without Playwright: Playwright keeps DevTools
+    # attached to the worker, and Chrome never stops a worker DevTools is
+    # attached to. It reaches nothing but its own loopback server.
+    echo "Running the approvals left open for seven minutes..."
+    docker run --rm \
+        --ipc=host \
+        -e HOME=/tmp \
+        "$(cat "$IIDFILE")" \
+        node tests/e2e/slowApproval.js
 }
 
 main "$@"