[SCUC 2026] Running multiple shops in parallel / changing ports

[lasomethingsomething]

User story

As a developer, I want to run multiple Shopware projects in parallel and adjust ports easily so local environments do not conflict.

Acceptance criteria

• allow overriding default local ports during setup
• show the chosen ports clearly after setup
• document how to change ports later
• prevent or detect port collisions during project creation

Readiness checklist

• Acceptance criteria are clearly defined.
• Backward compatibility impact addressed.
• Documentation written.
• Tests added or adjusted accordingly.