Rename post editor 'Schedule' tab to 'Channels'

The tab holds publish targets, per-platform settings, and labels — not
scheduling (the date/time control lives in the editor header). Renames the
i18n key posts.edit.tabs.schedule -> tabs.channels (Channels / Canais /
Canales) and the single $t reference. The scheduling button string and the
tab's internal value are untouched.

lang/en/posts.php

@@ -320,7 +320,7 @@
 
         'tabs' => [
             'preview' => 'Preview',
-            'schedule' => 'Schedule',
+            'channels' => 'Channels',
             'comments' => 'Comments',
             'comments_empty' => 'No comments yet.',
         ],

lang/es/posts.php

@@ -320,7 +320,7 @@
 
         'tabs' => [
             'preview' => 'Vista previa',
-            'schedule' => 'Programación',
+            'channels' => 'Canales',
             'comments' => 'Comentarios',
             'comments_empty' => 'Todavía no hay comentarios.',
         ],

lang/pt-BR/posts.php

@@ -320,7 +320,7 @@
 
         'tabs' => [
             'preview' => 'Pré-visualização',
-            'schedule' => 'Agendamento',
+            'channels' => 'Canais',
             'comments' => 'Comentários',
             'comments_empty' => 'Nenhum comentário ainda.',
         ],

resources/js/components/posts/editor/PostEditorTabs.vue

@@ -93,7 +93,7 @@ defineExpose({
     <Tabs v-model="activeTab" class="h-full flex flex-col">
         <TabsList class="mx-4 mt-4 w-fit shrink-0 self-start">
             <TabsTrigger value="preview">{{ $t('posts.edit.tabs.preview') }}</TabsTrigger>
-            <TabsTrigger value="schedule">{{ $t('posts.edit.tabs.schedule') }}</TabsTrigger>
+            <TabsTrigger value="schedule">{{ $t('posts.edit.tabs.channels') }}</TabsTrigger>
             <TabsTrigger value="comments">{{ $t('posts.edit.tabs.comments') }}</TabsTrigger>
         </TabsList>