Admin: gestión de usuarios (buscar, banear/desbanear)

- lib/admin-users.ts: searchAccounts (acore_auth.account + account_banned + gmlevel),
  banAccount/unbanAccount por BD (autoritativo) con kick best-effort por SOAP.
  Baneo días<=0 = permanente (unbandate=bandate, convención AzerothCore); desactiva
  baneo activo previo antes de insertar el nuevo.
- API: GET /api/admin/users?q=, POST {accountId, action:ban|unban, reason, days} (403 sin admin).
- UI: /admin/users con AdminUsersManager (buscar por usuario/email, badges GM/online/baneado,
  banear con motivo+días o desbanear), enlace desde el índice del admin.
- i18n es/en (Admin): 14 claves nuevas.

Verificado: build OK, /admin/users 307→login, APIs 403 sin admin.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web-next/messages/en.json

@@ -332,7 +332,20 @@
     "goldAmount": "Gold amount",
     "goldPrice": "Price (€)",
     "goldUnit": "gold",
-    "noGold": "No gold options."
+    "noGold": "No gold options.",
+    "manageUsers": "Manage users",
+    "users": "Users",
+    "searching": "Searching…",
+    "userSearchPlaceholder": "Search account by username or email…",
+    "noUsers": "No matching accounts.",
+    "online": "Online",
+    "banned": "Banned",
+    "lastLogin": "Last login",
+    "ban": "Ban",
+    "unban": "Unban",
+    "banReasonPrompt": "Ban reason:",
+    "banDaysPrompt": "Ban days (0 = permanent):",
+    "confirmUnban": "Unban {name}?"
   },
   "Vote": {
     "title": "Vote for us",