Improve @/trustlab setup

[kilemensi]

Description

• Enable S3 storage only when necessary env vars are set, otherwise use local media folder (for development).
• Switch SMTP_PASS to be a secret instead of regular arg/env.
• compose now supports multiple --env-file args and hence no need to source env file(s) manually.

Type of change

• Chore

Screenshots

N/A

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation