feat: allow to declare custom db credentials in install scripts

[michivonah]

I removed the hard coded database credentials from the install.sh script and the script included in the manual-installations docs page. Instead I created three new variables (postgres_user, postgres_db, postgres_password) to declare the credentials, which then will be added as DATABASE_URL to the dokploy container.

If no password is defined by the user a random one will be generated with openssl rand --hex 32.

I tested the script on a blank debian 13 server and it worked as expected.

This increases the security of every new Dokploy installation by using a unique password.

This commit solves the issue Dokploy/dokploy#3384 of the dokploy repo.

[Siumauricio]

Hey, thank you for the PR, the current way use docker secrets this was released since the v0.26.6. version https://github.com/Dokploy/website/blob/main/apps/website/public/install.sh#L234-L251

[michivonah]

Thanks for the info. I didn't see that this had already been addressed in another PR.
I think the PR can be closed now.