Fix post-publish pipeline failures for v6.0.0-rc.6

promote-floating-tags.yml waited on rcourtman/pulse-agent:${TAG} and
promoted floating tags for it, but publish-docker.yml never pushes the
agent image — Pulse Agent ships as GitHub Release binaries
(publish-docker.yml line 199 confirms). The wait timed out after 5
minutes on every release since the pulse-agent push step was removed,
leaving floating tags unpromoted. Stripped the vestigial wait block,
the agent promote step, and the agent line in the summary. Updated
header comments in both files to drop the past-tense reference.

install-sh-smoke.yml booted jrei/systemd-debian:12 without
--cgroupns=host, so on GHA ubuntu-24.04 (cgroup v2 unified hierarchy)
the container's systemd PID 1 exited before mounting the cgroup tree
and the container disappeared during readiness polling. Added
--cgroupns=host, an explicit /run/lock tmpfs, and dropped --rm so the
container persists for diagnostic capture on failure (trap handles
cleanup). Added an "is container still running" probe inside the
readiness loop and richer diagnostic output on timeout.

.github/workflows/create-release.yml

@@ -1117,15 +1117,14 @@ jobs:
       app_version: ${{ needs.prepare.outputs.version }}
 
   # Defensive backup to promote-floating-tags.yml's workflow_run chain off
-  # publish-docker.yml. The chain works when publish-docker succeeds, but a
-  # publish-docker failure (rc.3 → rc.5 all failed at the now-removed
-  # pulse-agent push) silently left latest/major/minor tags unpromoted —
-  # customers pulling rcourtman/pulse:latest stayed on whatever the previous
-  # successful release tagged. Calling promote-floating-tags as workflow_call
-  # after validate_release_assets succeeds (which itself waits for the docker
+  # publish-docker.yml. The chain works when publish-docker succeeds, but
+  # when it fails the floating tags don't advance and customers pulling
+  # rcourtman/pulse:latest stay on whatever the previous successful release
+  # tagged. Calling promote-floating-tags as workflow_call after
+  # validate_release_assets succeeds (which itself waits for the docker
   # image to be pullable) guarantees the floating tags advance. Draft-only
-  # runs must not promote floating tags because the release is still private
-  # promotion state.
+  # runs must not promote floating tags because the release is still in
+  # private promotion state.
   promote_floating_tags:
     needs:
       - prepare