fix(tts): surface TTS errors from Python to Node.js logs and DB

- Python: capture tts_error_msg on exception, return in response
- Python: log tts_provider, minimax_api_key presence before call
- ffmpeg.ts: read tts_error from response, log and return it
- reels.ts: store TTS error in post.generationError for visibility

server/routes/reels.ts

@@ -640,6 +640,11 @@ async function processReelBackground(
 
         console.log(`⏱️ [Background] FFmpeg took ${(Date.now() - startTime) / 1000}s`);
 
+        if (ffmpegResult.ttsError) {
+            console.error(`❌ [Background] TTS FAILED: ${ffmpegResult.ttsError}`);
+            await storage.updatePost(postId, { generationError: `TTS échoué: ${ffmpegResult.ttsError}` });
+        }
+
         if (!ffmpegResult.success || !ffmpegResult.videoBase64) {
             throw new Error(ffmpegResult.error || 'Erreur de traitement vidéo FFmpeg');
         }