Foro: selector para fijar el personaje del autor

- Modal "Cambiar personaje" (diseño de la web) con filtro, avatar de raza,
  nombre en color de clase y subtítulo nivel/raza/clase.
- Barra "Publicas como: X · Cambiar personaje" sobre el formulario de respuesta
  (solo con sesión iniciada).
- Preferencia persistente en acore_web.forum_character (por cuenta), validada.
- resolvePosters usa el personaje fijado si existe; si no, el de más nivel.
- API /api/forum/character (GET lista + actual, POST fijar), gated por sesión.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web-next/app/[locale]/forum/topic/[topicId]/page.tsx

@@ -7,6 +7,8 @@ import {
   countPosts,
   resolvePosters,
   getUserPostCount,
+  getAccountCharactersForForum,
+  getForumCharacterPick,
 } from '@/lib/forum'
 import { formatForumDate } from '@/lib/forum-format'
 import { localizeWowheadLinks } from '@/lib/forum-wowhead'
@@ -17,6 +19,7 @@ import { PageShell } from '@/components/PageShell'
 import { ForumBreadcrumb } from '@/components/ForumBreadcrumb'
 import { Pagination } from '@/components/Pagination'
 import { ReplyForm } from '@/components/ReplyForm'
+import { ForumCharacterPicker } from '@/components/ForumCharacterPicker'
 import { EditPostForm } from '@/components/EditPostForm'
 import { ForumModActions } from '@/components/ForumModActions'
 import { WowheadRefresh } from '@/components/WowheadRefresh'
@@ -58,6 +61,10 @@ export default async function TopicPage({
     await Promise.all(uniquePosters.map(async (pid) => [pid, await getUserPostCount(pid)] as const)),
   )
 
+  const [forumChars, forumPick] = session.accountId
+    ? await Promise.all([getAccountCharactersForForum(session.accountId), getForumCharacterPick(session.accountId)])
+    : [[], null]
+
   const path = await getTopicPath(id, locale)
   const canReply = Boolean(session.username) && (!topic.locked || isMod)
 
@@ -199,7 +206,22 @@ export default async function TopicPage({
 
         {canReply ? (
           page === totalPages ? (
-            <ReplyForm topicId={id} />
+            <>
+              <ForumCharacterPicker
+                locale={locale}
+                initialChars={forumChars}
+                initialCurrent={forumPick}
+                labels={{
+                  postingAs: t('postingAs'),
+                  change: t('changeCharacter'),
+                  title: t('changeCharacter'),
+                  filter: t('filter'),
+                  empty: t('noCharacters'),
+                  auto: t('autoCharacter'),
+                }}
+              />
+              <ReplyForm topicId={id} />
+            </>
           ) : (
             <p className="forum-empty">
               <a href={`/forum/topic/${id}?page=${totalPages}`}>{t('replyOnLastPage')}</a>