Optional database observability for local setups

[lasomethingsomething]

User story

As a developer, I want optional database observability tooling in local Shopware setups, so I can inspect slow queries, database load, and performance bottlenecks during development.

Acceptance criteria

• optional local database observability can be enabled during or after setup
• the feature is explicitly optional and does not affect the default lightweight setup
• supported tooling is documented, e.g. PMM or equivalent
• the local setup shows where to access the observability UI
• disabling or removing it is documented

Readiness checklist

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