Admin: corregir columnas de account_access + enlace al panel en la cuenta

- Este build de AzerothCore usa account_access(AccountID, SecurityLevel), no el
  clásico (id, gmlevel). Se corrigen las 4 consultas (admin.ts, forum-perm.ts,
  forum.ts, admin-users.ts) -> isAdmin/forumIsModerator/gmlevel ahora funcionan.
- account page: enlace destacado al Panel de administración, visible solo si isAdmin.
- i18n es/en: Account.adminPanel.

Verificado: build OK; cuenta de prueba con SecurityLevel 3 (>= ADMIN_GMLEVEL) es admin.

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

web-next/messages/en.json

@@ -80,7 +80,8 @@
     "svcChangeEmail": "Change email",
     "svcVote": "Vote (points)",
     "svcRecruit": "Recruit a friend",
-    "svcStore": "Store (Battlepay)"
+    "svcStore": "Store (Battlepay)",
+    "adminPanel": "Admin panel"
   },
   "SelectAccount": {
     "title": "Select your game account",

web-next/messages/es.json

@@ -80,7 +80,8 @@
     "svcChangeEmail": "Cambiar email",
     "svcVote": "Votar (puntos)",
     "svcRecruit": "Recluta a un amigo",
-    "svcStore": "Tienda (Battlepay)"
+    "svcStore": "Tienda (Battlepay)",
+    "adminPanel": "Panel de administración"
   },
   "SelectAccount": {
     "title": "Selecciona tu cuenta de juego",