Database Cleanup: Implement cron job for retention

Description

Is your feature request related to a problem?
The database currently retains llm call rows, which can lead to unnecessary data accumulation.

Describe the solution you'd like

Implement a cron job in Kaapi to clean up user queries and llm responses older than a configurable value (1 hr, 1 day, 1 week, etc.).
Retain llm call metadata for debugging purposes but limit the retention of complete user queries and llm responses to a maximum of 2-3 days.
Ensure voicenotes remain in S3 for at least the TTL (1 hour) when using pre-signed URLs for TTS responses.

Original issue

Kaapi will keep only the llm call metadata and run a cron job to clean up the user query and llm response which are older than a configurable value (1 hr, 1 day, 1 week etc)
Reasons why we cannot immediately drop the messages:
- for tts response, if we send back a pre-signed url of the voicenote, we'll need to keep the voicenote in s3 for atleast the time period of the TTL (1 hour currently)
- debugging: on rare occassions, the complete user query and llm response has helped us debug certain issues with glific; but we only need that data for 2-3 days at max beyond which we can clean up the user query and llm response

Description