feat: media via AI, text via NormalBot only, ai_for_media toggle

- Text/interactive/button messages → NormalBot only, never escalates to AI
- Image/audio/video/document → AiBot.processMedia() if ai_for_media enabled,
  else falls back to category greeting menu
- AiBot.processMedia() uses permission_type context so AI acknowledges uploads
  for perm 3 and redirects others to their menu
- WpWebhook.handleMedia now calls BotRouter so the bot responds to media
- Admin UI: checkbox toggle "Procesar imágenes y archivos con IA" in AI tab
- categoryMenuFallback() extracted in BotRouter as shared helper

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

admin/v1/WpWebhook.php

@@ -351,6 +351,9 @@ class WpWebhook
         self::saveWebhookLog('messages', $ctx['from'], $ctx['name'], $type, $preview);
         self::saveConversation($ctx, $preview, $mediaId);
         self::forwardToCompany($ctx, $preview, $mediaId);
+        if (self::$currentCompany !== null) {
+            BotRouter::route(self::$currentCompany, $ctx, $caption, $type);
+        }
     }
 
     private static function handleLocation(array $msg, array $ctx): void