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/channel/evolution/evolution.channel.service.ts

@@ -165,7 +165,7 @@ export class EvolutionStartupService extends ChannelStartupService {
             openAiDefaultSettings.speechToText &&
             received?.message?.audioMessage
           ) {
-            messageRaw.message.speechToText = await this.openaiService.speechToText(received, this);
+            messageRaw.message.speechToText = `[audio] ${await this.openaiService.speechToText(received, this)}`;
           }
         }