PC set-up: one line per PC (/setup/<name>.ps1), the admin laptop always let in, and the admin check no longer breaks the script

- the inserted administrator check split the header comment, leaving '} for ... run ONCE' as code: WS and SC
  join.ps1 failed to parse (Windows' parser: Missing opening '(' after keyword 'for'); now after the whole line
- site.admin_ips / admin_keys (laptop 10.6.7.38, fixed in UniFi) go into every PC script's firewall rule and key
  files, and into the Mac join line, so running a set-up again never shuts the laptop out
- scripts verified by Windows' own PowerShell parser on the NA Lighting PC

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

config.json

@@ -1382,7 +1382,13 @@
     ],
     "ingest_name": "NA Ingest",
     "live_services": [],
-    "name": "North Attleboro"
+    "name": "North Attleboro",
+    "admin_ips": [
+      "10.6.7.38"
+    ],
+    "admin_keys": [
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPKCGDLncJQfNPpoZUy/5BQWGNtyaU1/xKXwHQWx3ETa christian-laptop@waters"
+    ]
   },
   "spotify": {
     "name": "Christian EDM 2026",