feat(Typebot): add splitMessages and timePerChar fields to Typebot models

- Introduced `splitMessages` and `timePerChar` fields in the Typebot and TypebotSetting models with default values.
- Created a migration script to update the database schema accordingly.
- Updated audio message handling to prepend `[audio]` to transcriptions for better clarity in message context.

src/api/integrations/chatbot/flowise/services/flowise.service.ts

@@ -72,7 +72,7 @@ export class FlowiseService extends BaseChatbotService<FlowiseModel> {
         this.logger.debug(`[Flowise] Downloading audio for Whisper transcription`);
         const transcription = await this.openaiService.speechToText(msg, instance);
         if (transcription) {
-          payload.question = transcription;
+          payload.question = `[audio] ${transcription}`;
         }
       } catch (err) {
         this.logger.error(`[Flowise] Failed to transcribe audio: ${err}`);