feat: NLU routing + audio/image transcription via AI

- NluRouter in AiBot: builds permission-filtered flow catalog, asks AI
  to route user intent to exact flow key or return chat response
- MediaTranscriber: downloads WA media, transcribes audio (Whisper/Gemini),
  extracts image intent (OpenAI/Gemini/Claude vision)
- BotRouter hybrid: text → NormalBot → NLU fallback if no match;
  audio/image → transcribe → NLU route; sends transcript preview first
- Admin IA tab: NLU checkbox with description
- Per-company nlu flag saved in config_json

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

services/BotRouter.php

@@ -107,24 +107,75 @@ class BotRouter
 
     private static function runHybridBot(array $company, array $context, string $input, string $inputType): ?array
     {
-        $config = self::getConfig($company);
+        $config     = self::getConfig($company);
+        $nluEnabled = (bool)($config['nlu'] ?? false);
+        $aiEnabled  = (bool)($config['ai_for_media'] ?? true);
 
-        // Media (image/audio/video/document) → AI handles it if enabled
+        // ── Media (audio/imagen) ──────────────────────────────────────────────
         if (self::isMediaType($inputType)) {
-            $aiEnabled = (bool)($config['ai_for_media'] ?? true);
             if (!$aiEnabled) {
                 return self::categoryMenuFallback($company, $context, $config);
             }
+
+            if ($nluEnabled && in_array($inputType, ['audio', 'image'], true)) {
+                $text = $inputType === 'audio'
+                    ? MediaTranscriber::transcribeAudio($input, $company)
+                    : MediaTranscriber::extractFromImage($input, $company);
+
+                if ($text !== null && trim($text) !== '') {
+                    self::log("NLU media [{$inputType}]: texto extraído → \"{$text}\"");
+                    // Confirmar al usuario lo que entendió
+                    $prefix = $inputType === 'audio' ? '🎤 Transcripción' : '🖼️ Imagen analizada';
+                    WhatsAppSender::sendText(
+                        $context['from'],
+                        "{$prefix}: _{$text}_",
+                        $context['phone_number_id'] ?? ''
+                    );
+                    return self::runNluOnText($company, $context, $text, $config);
+                }
+            }
+
             return AiBot::processMedia($company, $context, $inputType, $input);
         }
 
-        // Text / interactive / button → NormalBot only, never AI
+        // ── Texto / interactivo: NormalBot primero ────────────────────────────
         $response = self::runNormalBot($company, $context, $input, $inputType);
         if ($response !== null) {
             return $response;
         }
 
-        // NormalBot returned null → show the category greeting menu as fallback
+        // NormalBot no reconoció → NLU si está activo, si no menú categoría
+        if ($nluEnabled && $inputType === 'text') {
+            return self::runNluOnText($company, $context, $input, $config);
+        }
+
+        return self::categoryMenuFallback($company, $context, $config);
+    }
+
+    private static function runNluOnText(array $company, array $context, string $input, array $config): ?array
+    {
+        $result = AiBot::routeOrChat($company, $context, $input);
+
+        if ($result['action'] === 'route') {
+            $key    = $result['key'];
+            $botCtx = ConversationContext::getOrCreate((int)$company['id'], $context['from'], 'normal');
+            ConversationContext::updateNode((int)$botCtx['id'], $key);
+            self::log("NLU: {$context['from']} → flow [{$key}]");
+            // Ejecutar con input vacío — NormalBot retoma current_node
+            return NormalBot::process($company, $context, '');
+        }
+
+        $text = trim($result['text'] ?? '');
+        if ($text !== '') {
+            self::log("NLU: {$context['from']} → chat libre");
+            return [
+                'action'  => 'send',
+                'type'    => 'text',
+                'to'      => $context['from'],
+                'payload' => json_encode(['text' => $text]),
+            ];
+        }
+
         return self::categoryMenuFallback($company, $context, $config);
     }