Fix dead/incorrect vars in Plugin/ found during full codebase audit

- WEBGUI_PHP_WAIT was referenced by webgui_watchdog.sh but never defined
  in master.conf, always silently falling back to a hardcoded default
- arrs.php/confform.php still pointed at Media/ for arr cleanup/discovery
  scripts moved to Arrs_Stack/ in b4bc926 — broke the Arrs page's stats
  and the per-script settings editor for those scripts
- docker_folders.php read directly from the optional folder.view3 plugin's
  file instead of Varaverk's own docker_folders.json (the primary store
  since the Docker tab got its own config) — left the Monitor page's
  Docker Folders widget empty on any host without folder.view3 installed
- vv_wd_remote_data() read remote watchdog state files from hardcoded
  /tmp or /boot/config paths instead of the remote's actual STATE_DIR
  (which resolves dynamically and can differ under flash mode) — remote
  node's Watchdog panel was always empty; same wrong path also used for
  two local reads (system_watchdog_oom.db, watchdog_appdata_growth.db)
- rsync.php referenced a {HOST}_MONTHLY_SYNC_SHARES conf var that never
  existed (monthly_maintenance.sh has no rsync section) — nulled out to
  match the existing pattern used for the fallback window
- vv_arr_node_names() did a pointless identity array_map
- vv_dk_webui() had its own duplicate local-IP resolution instead of
  using vv_local_ip(), despite config.php's comment claiming that exact
  duplication was already consolidated

Plugin/unraid/include/docker.php

@@ -97,12 +97,7 @@ function vv_dk_webui(string $name, array $portMap): string {
     if (!preg_match('/<WebUI>(.*?)<\/WebUI>/s', $xml, $m)) return '';
     $url = trim($m[1]);
     if (!$url) return '';
-    static $localIp = null;
-    if ($localIp === null) {
-        $localIp = trim(shell_exec("ip route get 8.8.8.8 2>/dev/null | awk '/src/{for(i=1;i<=NF;i++)if(\$i==\"src\")print \$(i+1)}'") ?: '');
-        if (!$localIp) $localIp = gethostbyname(gethostname());
-    }
-    $url = str_replace('[IP]', $localIp, $url);
+    $url = str_replace('[IP]', vv_local_ip(), $url);
     $url = preg_replace_callback('/\[PORT:(\d+)\]/', fn($pm) => $portMap[$pm[1]] ?? $pm[1], $url);
     return $url;
 }