Steps to reproduce the issue

1. Open Joomla Installer (version 6.0.2) on a fresh installation.
2. Fill in the "Super User" step:
   • Enter a username (e.g., "test")
   • Enter a password less than 12 characters (e.g., "shortpass")
   • Fill the other required fields (email, real name)
3. Click "Next" to proceed to the Database Configuration step.
4. Fill in database details (DB host, username, password, database name).
5. Complete the installation process.
6. At the end, Joomla shows an error saying the Super User password is invalid.

Expected result

• The installer should validate the Super User password immediately.
• User should not be able to proceed to the next step until the password meets the minimum requirement of 12 characters.
• A clear error message should appear before advancing to Database Configuration.

Actual result

• The installer allows moving to the Database Configuration step even when the password is too short.
• Only at the final step, after filling in all database information, does it display an error about the password.
• This may cause confusion and wasted time for users.

System information (as much as possible)

• Joomla version: 6.0.2
• PHP version: 8.3 (running on Docker)
• Database: MySQL 8.0 (running on Docker)
• Browser: Chrome 144.0.0.0 (Windows 10)
• Installation method: Docker compose local environment

Additional comments

• Adding real-time validation for the Super User password at the installer step would improve UX significantly.
• A screenshot of the Super User step with a short password entered can help reviewers reproduce the issue quickly.