Structural reorganization: watchdog taxonomy + server_reboot integration

Watchdog renames and moves:
  system_watchdog.sh → stability_watchdog.sh (last line of defense — reboots)
  storage_watchdog.sh → Watchdogs/System/storage_watchdog.sh
  webgui_restart.sh → Watchdogs/System/webgui_watchdog.sh (renamed to match folder convention)

New thin orchestrator:
  Watchdogs/system_watchdog.sh — runs SYSTEM_WATCHDOG_SCRIPTS from master.conf
  Sits between docker_watchdog and stability_watchdog in the orchestrator tier chain
  System/ subfolder is the growth seam for future system component watchdogs

master.conf:
  WATCHDOG_ORCHESTRATOR_SCRIPTS updated — storage removed, system_watchdog added as tier
  SYSTEM_WATCHDOG_SCRIPTS array added — storage + webgui

server_reboot.sh:
  Calls array_stopping.sh before VM shutdown for guaranteed safe array stop
  Removed raw rc.docker stop and exit trap — orchestrator owns container shutdown

Orchestrators/sunday_morning_coffee_report.sh

@@ -480,7 +480,7 @@ if [[ -f "$SYS_WATCHDOG_STATE_FILE" ]]; then
         issue "  Last run: $(_fmt_uptime "$_sw_ago") ago — watchdog_orchestrator may not be running"
     fi
 else
-    issue "  system_watchdog has never run (state file missing)"
+    issue "  stability_watchdog has never run (state file missing)"
 fi
 
 if [[ -f "$SYS_WATCHDOG_STATE_FILE" ]]; then