Wire up unused config vars found in follow-up audit pass

TRANSCODE_LOG_RETENTION was documented as trimming the daily transcode log
but never referenced — log grew unbounded. TRANSCODE_ORPHAN_AGE was shown in
--status but never used, so empty session folders were deleted immediately
instead of after the documented grace period, risking a race against ffmpeg
creating a folder just before writing its first segment.

docker_watchdog.sh's daemon-health thresholds were only hardcoded fallbacks
despite comments claiming they were master.conf-configurable, and it
referenced a heartbeat feature that was never implemented (that's owned by
watchdog_orchestrator.sh, its caller) — added the three thresholds to
master.conf for real and removed the stale heartbeat claim.

Also added the missing HOSTN_PARTNERSHIP_SERVICES_STACK block to
host.conf.template (containers.sh already read it via detect_hosts, just
never had a template entry) and corrected play_state_sync.sh's doc comment
for PLAY_SYNC_TYPES' actual default.

Configurations/master.conf

@@ -813,6 +813,11 @@
 # Notification batching — one summary per cycle instead of one ping per event
     WATCHDOG_BATCH_NOTIFY=true
 
+# Docker daemon health check — hung daemon detection at the start of each cycle
+    WATCHDOG_DAEMON_TIMEOUT=20            # seconds — timeout for all docker commands
+    WATCHDOG_DAEMON_STRIKE_LIMIT=3        # consecutive failed checks before restart attempt
+    WATCHDOG_DAEMON_RESTART_WAIT=900      # seconds to wait after restart before verifying
+
 # Appdata size monitoring — two-part catch-all for runaway growth and oversized log files.
 #
 # Part 1 — Growth rate (zero-config):