fix(watchdogs): Tailscale false positive + system watchdog banner

network_watchdog: Tailscale JSON uses "BackendState": "Running" (with space)
but grep pattern matched "BackendState":"Running" (no space) — always failed.
Switched to grep -qE with \s* to handle both forms.

system_watchdog: add echo banner at run start so its output is visually
separated from docker_watchdog in orchestrator logs. Previously appeared
as a continuation of the docker section since docker_watchdog has a banner
but system_watchdog did not.

Watchdogs/system_watchdog.sh

@@ -84,6 +84,8 @@ fi
 # ==============================================================================================
 # ━━━ Run Sequence ━━━
 # ==============================================================================================
+echo "━━━ $ICON_SHIELD System Watchdog — $(date '+%Y-%m-%d %H:%M:%S') ━━━"
+
 START=$(date +%s)
 PASSED=()
 FAILED=()