feat: NLU fallback — route unrecognized text to AI in hybrid+NLU mode

NormalBot.process() gains suppressFallback param. When true, steps 7-8
(greeting menu fallback, static fallback text) return null instead of
responding, letting BotRouter hand off to NLU/AI.

BotRouter.runHybridBot() passes suppressFallback=$nluEnabled so that:
- NLU on: unrecognized text → NLU → route to flow or AI chat
- NLU off: existing fallback behavior unchanged
- Commands, active flows, first-session greeting: always unaffected

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

services/BotRouter.php

@@ -87,12 +87,12 @@ class BotRouter
         };
     }
 
-    private static function runNormalBot(array $company, array $context, string $input, string $inputType): ?array
+    private static function runNormalBot(array $company, array $context, string $input, string $inputType, bool $suppressFallback = false): ?array
     {
         if ($inputType === 'interactive' || $inputType === 'button') {
             return NormalBot::processInteractive($company, $context, $input);
         }
-        return NormalBot::process($company, $context, $input);
+        return NormalBot::process($company, $context, $input, $suppressFallback);
     }
 
     private static function runAiBot(array $company, array $context, string $input): ?array
@@ -140,7 +140,9 @@ class BotRouter
         }
 
         // ── Texto / interactivo: NormalBot primero ────────────────────────────
-        $response = self::runNormalBot($company, $context, $input, $inputType);
+        // suppressFallback=true cuando NLU activo: si NormalBot no reconoce, retorna null
+        // y dejamos que NLU decida en vez de mostrar el menú de bienvenida como fallback
+        $response = self::runNormalBot($company, $context, $input, $inputType, $nluEnabled);
         if ($response !== null) {
             return $response;
         }