ci: build, test, and run Signage inside a pinned Ekklesia on every change

Signage had no CI. Its tests passed while three defects shipped that
appear only inside Ekklesia, in a real browser. Every job now assembles
Signage into a pinned platform commit, as an instance does, and
installs that workspace with --frozen-lockfile:
- lint, typecheck, test: Signage's own checks;
- build: the platform's gates against exactly this module set (boundary
  rules, module manifest, migrations), then the build;
- integration: the deployment image from the platform's Dockerfile,
  then the platform's split-topology smoke. It pairs a kiosk display,
  restarts it on the same profile, and runs the scenarios in
  ci/display-scenarios.

The supporting files:
- ci/platform.env pins one platform commit. ci/assemble.sh fetches the
  platform's main and refuses a pinned commit that is not on it, so CI
  only runs reviewed platform code.
- ci/pnpm-lock.yaml is the assembled workspace's lockfile, regenerated
  with ci/update-lock.sh.

Same trust rules as the platform: actions pinned by SHA,
persist-credentials false, no secrets, no pull_request_target.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

ci/integration.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+# Signage inside Ekklesia, end to end: builds the deployment image from the assembled workspace with
+# the platform's own Dockerfile, then runs the platform's split-topology deployment smoke against it
+# with the display-device scenarios listed in ci/display-scenarios. A disposable PostgreSQL and object
+# store, generated secrets, and an explicit migration apply against that fresh database only; nothing
+# is pushed, published, or logged in to. The image is removed afterwards.
+#
+#   bash ci/integration.sh            (after bash ci/assemble.sh)
+set -Eeuo pipefail
+
+root="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)"
+workspace="$root/build/workspace"
+[[ -f "$workspace/deploy/Dockerfile" ]] || {
+  echo "integration: run bash ci/assemble.sh first." >&2
+  exit 1
+}
+
+image="signage-ci:${GITHUB_SHA:-local}-${GITHUB_RUN_ID:-0}-${GITHUB_RUN_ATTEMPT:-1}"
+trap 'docker image rm --force "$image" >/dev/null 2>&1 || true' EXIT
+
+scenarios="$(sed -e 's/#.*//' -e '/^[[:space:]]*$/d' "$root/ci/display-scenarios" | tr '\n' ' ')"
+[[ -n "${scenarios// /}" ]] || {
+  echo "integration: ci/display-scenarios lists no scenario." >&2
+  exit 1
+}
+
+DOCKER_BUILDKIT=1 docker build --quiet --file "$workspace/deploy/Dockerfile" --tag "$image" \
+  "$workspace" >/dev/null
+echo "integration: built the deployment image with Signage; scenarios: ${scenarios}"
+
+cd "$workspace"
+EKKLESIA_SMOKE_TOPOLOGY=split \
+  EKKLESIA_SMOKE_IMAGE="$image" \
+  EKKLESIA_SMOKE_DISPLAY_DEVICE=1 \
+  EKKLESIA_SMOKE_DISPLAY_SCENARIOS="$scenarios" \
+  EKKLESIA_SMOKE_WATCH_MS=120000 \
+  EKKLESIA_SMOKE_RECYCLE_WATCH_MS=120000 \
+  bash scripts/smoke-deploy.sh