Bring script headers onto the template and close safeguard gaps

Headers claimed protections the code never had, and several destructive paths had no
guard against a collapsed config value.

System_Essentials/rsync_stop.sh

@@ -40,6 +40,35 @@
 #   If remote unreachable → skips remote cleanly, logs warning.
 #
 # ==============================================================================================
+# DESIGN PRINCIPLES
+# ==============================================================================================
+#
+# Stop the Transfer, Not the Schedule
+#   The default mode kills only the rsync subprocess and lets the orchestrator notice
+#   the exit and wind down on its own. Killing the orchestrator too would abandon the
+#   remaining shares silently; letting it finish its own loop keeps the schedule honest
+#   about what ran and what did not.
+#
+# Exact-Name Process Matching
+#   Targets are found with pgrep -x rsync — exact process name, never a pattern match
+#   against a command line. A loose pattern on a box running arbitrary containers could
+#   match something that merely mentions rsync in its arguments.
+#
+# Liveness Checked Before Every Signal
+#   kill -0 confirms a PID is still alive immediately before signalling it. PIDs are
+#   reused, and a transfer that exited on its own between discovery and signalling must
+#   not have its number sent a kill.
+#
+# Interrupting Is Safe by Construction
+#   rsync runs with --partial, so a killed transfer resumes rather than restarting.
+#   That is what makes stopping mid-sync a routine operation rather than a costly one.
+#
+# Clean Up What the Interruption Left
+#   A killed rsync leaves its lock file behind and may leave profile containers stopped.
+#   Both are cleared afterwards, so the next scheduled run is not blocked by a lock
+#   whose owner no longer exists.
+#
+# ==============================================================================================
 # OPERATIONAL SAFEGUARDS
 # ==============================================================================================
 #
@@ -61,6 +90,31 @@
 #   Remote containers deferred to docker_watchdog.sh.
 #
 # ==============================================================================================
+# CONFIGURATION
+# ==============================================================================================
+#
+# master.conf
+#
+#   LOCK_DIR
+#       Directory holding rsync and orchestrator lock files. Scanned after a kill to
+#       clear locks whose owning PID is gone.
+#
+#   DOCKER_TIMEOUT
+#       Timeout applied to the docker calls used when recovering containers a killed
+#       rsync left stopped.
+#
+#   PROFILE_CRITICAL_CONTAINER_NAMES
+#       Per-profile container lists — used to work out which containers an interrupted
+#       profile sync had stopped and therefore needs restarting.
+#
+#   SSH_KEY / SSH timeouts
+#       Used to reach the partner when stopping its rsync as well.
+#
+# host*.conf
+#
+#   HOST*  — resolved via detect_hosts() for MY_ID and remote routing
+#
+# ==============================================================================================
 # RUNTIME MODES
 # ==============================================================================================
 #