Improve DX: Show container names and database credentials for easier environment variable setup

[kleintonno]

Currently, there is no straightforward way to find a resource's container name in the Coolify UI.
Users have to resort to workarounds like checking the deployment logs or looking up the resource
UUID in the URL bar. This makes it unnecessarily tedious to set up environment variables like
DB_HOST or DATABASE_URL that require the container name of another resource on the same server.

Additionally, database credentials (password, username, connection URL) on the configuration page
cannot be copied with a single click - users have to manually select and copy text from inputs.

This proposes three improvements:

1. Container name display - Show the container name with a copy button in the heading navbar
   for applications and databases

2. Database references in Add Env modal - When adding a new environment variable for an
   application, show a dropdown of databases on the same server with clickable preset buttons
   (DB_HOST, DB_PASSWORD, DATABASE_URL, DB_CONNECTION, etc.) that prefill the form

3. Copy buttons for database credentials - Add a copyable option to the input component and
   use it on database configuration pages for credentials and connection URLs