Foro: restaurar posts y temas borrados (moderadores)

- lib/forum.ts: getTopic/getPosts/countPosts aceptan includeDeleted (mods ven lo
  borrado); Post.deleted y TopicFull.deleted.
- API: PUT /api/forum/post restaura post (mod-only); moderate action 'restore'
  restaura tema (usa includeDeleted al leer el tema).
- UI: posts borrados atenuados con badge y botón Restaurar (PostActions);
  TopicModBar muestra banner + Restaurar tema cuando el tema está borrado.
- i18n es/en: Forum.restore, restoreTopic, deletedMark.

Verificado: build OK, PUT post y moderate restore 401 sin sesión, /forum 200.

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

web-next/messages/en.json

@@ -294,7 +294,10 @@
     "resultsCount": "{count} result(s) for “{query}”.",
     "in": "in",
     "replyOnLastPage": "Go to the last page to reply",
-    "moveTopic": "Move to"
+    "moveTopic": "Move to",
+    "restore": "Restore",
+    "restoreTopic": "Restore topic",
+    "deletedMark": "Deleted"
   },
   "Admin": {
     "title": "Admin panel",