Fix NLU flow: media_id, upload perm, catalog filter, nlu_description field

- WpWebhook: inject media_id into context before calling BotRouter so
  MediaTranscriber can download audio/image (was passing caption='')
- BotRouter: use context['media_id'] for transcription (non-breaking fallback)
- AiBot::processMedia: fix canUpload to include permType 1 (solo reporta)
- AiBot::buildFlowCatalog: include text flows that have nlu_description set
- DashboardController + index.php: add nlu_description field per flow card

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

admin/v1/WpWebhook.php

@@ -480,6 +480,8 @@ class WpWebhook
         $isNew = self::saveConversation($ctx, $preview, $mediaId);
         self::forwardToCompany($ctx, $preview, $mediaId);
         if ($isNew && self::$currentCompany !== null) {
+            // media_id in context so BotRouter/MediaTranscriber can download the file
+            $ctx['media_id'] = $mediaId;
             BotRouter::route(self::$currentCompany, $ctx, $caption, $type);
         }
     }