Improve Data at Rest Security - Encrypt tables passwords in database

We should encrypt the tables passwords in the database as a best practice.

> This PR will store the DB password in unencrypted format. While I realise we are presenting this to the user unencrypted, it does go against "data at rest security". This may not be super critical due to DB accessibility on the platform in our case at FFC, but for self hosted this may be a no-go due to regulations around this area for their industry (hippa?) and their architecture (e.g. location of database)?

_Originally posted by @Steve-Mcl in https://github.com/FlowFuse/flowfuse/issues/5764#issuecomment-3112927321_