Fix Whisper response parsing: query param + plain text fallback

- Send response_format=json as URL query param (not form field)
- If JSON parse yields empty text, fall back to raw plain-text body
- Prevents false 'error' logs when Whisper returns plain text

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

app/Services/TelegramBotService.php

@@ -250,15 +250,29 @@ class TelegramBotService
         }
 
         try {
+            // response_format como query param (algunos servidores no lo leen del form)
+            $url = rtrim($whisperUrl, '?') . (str_contains($whisperUrl, '?') ? '&' : '?') . 'response_format=json';
+
             $response = Http::timeout(60)
                 ->withBasicAuth('whisper', $whisperToken)
                 ->attach('audio_file', $audioContent, 'audio.ogg')
-                ->post($whisperUrl, ['response_format' => 'json']);
+                ->post($url);
 
             $tiempoMs = (int) ((microtime(true) - $inicio) * 1000);
-            $json     = $response->json();
-            $texto    = trim($json['text'] ?? $json['transcription'] ?? '');
-            $ok       = $response->successful() && $texto !== '';
+
+            // Intentar JSON primero, luego texto plano como fallback
+            $json  = $response->json();
+            $texto = trim($json['text'] ?? $json['transcription'] ?? '');
+
+            if ($texto === '' && $response->successful()) {
+                // El servidor devolvió texto plano
+                $raw = trim($response->body());
+                if ($raw !== '' && ! str_starts_with($raw, '{') && ! str_starts_with($raw, '[')) {
+                    $texto = $raw;
+                }
+            }
+
+            $ok = $response->successful() && $texto !== '';
 
             AiUsageLog::registrar([
                 'servicio'        => 'whisper',