Fix pipeline compatibility with Open WebUI

[tdiprima]

Description

Uploading the original pipeline to Open WebUI was failing. This update makes minor but critical improvements to the pipeline:

1. The setting of environment variables has been updated because Open WebUI likes this format better.
2. Updated default value for DB_HOST to prevent misconfigurations when environment variables are not set.
3. Added required metadata.
4. Minor formatting adjustments to make sure the code is valid.

Testing

Validated changes using Open WebUI to ensure the updated code gets imported without errors, and works as expected.