Foro: edición/borrado de posts, moderación de temas y búsqueda

Portado desde forum/db.py + forum/permissions.py de Django:
- lib/forum-perm.ts: forumIsModerator (gmlevel >= FORUM_MOD_GMLEVEL) y
  canEditPost (autor o moderador).
- Edición y borrado lógico de posts (autor o mod), respetando tema bloqueado,
  con validación de longitud mínima (plainLength).
- Moderación de temas (solo mod): bloquear/desbloquear, fijar/no fijar, borrar.
- Búsqueda de temas por título/contenido (searchTopics/countSearchTopics)
  con página /forum/search y buscador en el índice.
- API: PATCH/DELETE /api/forum/post, POST /api/forum/moderate (401/403 correctos).
- UI: PostActions, TopicModBar, ForumSearchBox; marca "editado" y "[Fijado]".
- i18n: 22 claves nuevas en es/en.

Verificado: build OK, /forum y /forum/search 200, APIs 401 sin sesión.

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

web-next/messages/en.json

@@ -268,7 +268,29 @@
     "sending": "Sending…",
     "loginToPost": "Sign in to participate.",
     "emptyError": "Fill in all fields.",
-    "genericError": "Something went wrong. Please try again later."
+    "genericError": "Something went wrong. Please try again later.",
+    "moderation": "Moderation",
+    "lock": "Lock",
+    "unlock": "Unlock",
+    "pin": "Pin",
+    "unpin": "Unpin",
+    "pinned": "Pinned",
+    "deleteTopic": "Delete topic",
+    "confirmDeleteTopic": "Are you sure you want to delete this topic?",
+    "edit": "Edit",
+    "delete": "Delete",
+    "save": "Save",
+    "cancel": "Cancel",
+    "confirmDeletePost": "Are you sure you want to delete this post?",
+    "tooShort": "The message is too short (minimum 5 characters).",
+    "topicLocked": "This topic is locked.",
+    "editedMark": "edited",
+    "search": "Search",
+    "searchPlaceholder": "Search the forum…",
+    "searchHint": "Type at least 2 characters to search.",
+    "noResults": "No results for “{query}”.",
+    "resultsCount": "{count} result(s) for “{query}”.",
+    "in": "in"
   },
   "Admin": {
     "title": "Admin panel",