Fix backend patch never loading at boot: schedule deferred middlewared restart

PREINIT initshutdownscripts are executed by middlewared itself
(ix-preinit.service, ordered after ix-zfs pool import), so the running
process had already imported the stock modules when apply.sh patched
them in the overlay — S3/B2 support silently reverted on every reboot
until something restarted middlewared. install.sh masked the bug with
its explicit restart.

apply.sh now detects boot context (parent process is middlewared) and
schedules a single detached restart via a transient systemd unit
(truecloud-mw-restart, After=multi-user.target and ix-postinit.service).
Manual runs never trigger a restart.

create_task.py verify no longer trusts hook_status.json alone: it
compares the middlewared main-process start time (derived from
/proc/<pid>/stat and btime) against patched_at and reports FAIL when
the running process predates the patch.

recover.sh and uninstall.sh cancel a still-queued deferred restart
before their own; docs updated to match the real boot ordering.

install.sh

@@ -10,13 +10,15 @@
 #
 # What this does:
 #   1. Registers a PREINIT initshutdownscript so patch/apply.sh re-runs on
-#      every boot before middlewared starts.
+#      every boot. At boot, apply.sh re-patches the overlay and schedules a
+#      one-time deferred middlewared restart to load the patched modules
+#      (PREINIT runs after middlewared starts, so a restart is required).
 #   2. Applies the patches immediately (no reboot required).
 #   3. Restarts middlewared so the backend change takes effect now.
 
 set -euo pipefail
 
-VERSION="0.0.3"
+VERSION="0.0.4"
 
 # The directory containing install.sh is the permanent install location.
 PATCH_DIR="$(cd "$(dirname "$0")" && pwd)"