ci: the integration job removes its stacks even when the runner kills it

The platform's rule (its ci-sweep.sh, docs/development/security.md),
applied to the one Signage job that starts Docker stacks:
- it has its own EKKLESIA_CI_JOB_KEY;
- it sweeps stale CI stacks from the runner before it starts;
- it removes its own stacks in a final `if: always()` step, which
  tolerates a failed assembly, since nothing was started then;
- the image ci/integration.sh builds is named and labeled as a CI stack
  of this run and job, with the time CI built it, so the sweep finds it.

ci/platform.env moves to the platform commit that adds the sweep
(Ekklesia #60). The assembled lockfile is unchanged, and still passes a
frozen install.

Verified: SIGKILL of the integration script's whole process group
mid-run left 11 resources (2 containers, 4 networks, 4 volumes and the
image). `ci-sweep.sh --job` removed exactly those 11. A normal run
passes, and the job sweep after it finds nothing.

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

ci/platform.env

@@ -3,4 +3,4 @@
 #
 # Move it deliberately: change the commit, run `bash ci/update-lock.sh`, and commit both.
 EKKLESIA_PLATFORM_REPOSITORY=https://git.riverofglorymn.org/River_of_Glory_Church/Ekklesia.git
-EKKLESIA_PLATFORM_COMMIT=f50e8f42018c15698709739e2ba54771e97df08a
+EKKLESIA_PLATFORM_COMMIT=00e544125b855372e0f173db33323a57ac357d02