ci(e2e): run Playwright from the prebuilt image instead of downloading browsers (refs #73)

The verify-e2e lane downloaded ~150 MB of Chromium (npx playwright install) on
every verify-stack run. Use the official mcr.microsoft.com/playwright image with
browsers pre-baked; npm install still pins @playwright/test from tests/e2e, and
the image tag is kept in lockstep with that version. Verified the exact
create + docker cp + start flow launches the baked browser with no download.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

infra/run-e2e-check.sh

@@ -3,10 +3,14 @@
 # Walking-skeleton e2e (S-08d) against an ALREADY-RUNNING full stack: drive the self-service portal
 # in a real browser through mock-DigiD login → submit → confirmation (login → BFF → domain).
 #
-# Runs Playwright INSIDE the compose network (a node container on `cg`), so the browser reaches
+# Runs Playwright INSIDE the compose network (a container on `cg`), so the browser reaches
 # Keycloak by service name (keycloak:8080) — the same authority the BFF validates against, so the
 # token issuer matches (ADR-0010). The spec is copied into the container (docker cp), not mounted,
 # so it leaves no root-owned files on the host. The caller owns stack bring-up + teardown.
+#
+# Uses the official Playwright image with browsers pre-baked, instead of downloading ~150 MB of
+# Chromium on every run (issue #73). The image tag MUST match tests/e2e/package.json's
+# @playwright/test version — bump both together.
 set -euo pipefail
 
 here="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
@@ -19,7 +23,7 @@ echo ">> running Playwright e2e on network $net against http://self-service"
 
 cid="$(docker create --network "$net" -w /e2e --ipc=host \
   -e SELF_SERVICE_URL=http://self-service \
-  node:24 sh -c 'npm install --no-audit --no-fund && npx playwright install --with-deps chromium && npx playwright test')"
+  mcr.microsoft.com/playwright:v1.61.1-noble sh -c 'npm install --no-audit --no-fund && npx playwright test')"
 trap 'docker rm -f "$cid" >/dev/null 2>&1 || true' EXIT
 docker cp "$root/tests/e2e/." "$cid:/e2e" >/dev/null
 docker start -a "$cid"