Add draft/published functionality

[yepzdk]

Description

Add a published/active boolean (or status enum) to Route (and possibly PointOfInterest). Filter unpublished content from the API and show status in admin with ability to toggle.

Implementation

• Add a published field to src/Entity/Route.php (and possibly PointOfInterest)
• Create a Doctrine migration
• Add an API Platform query extension to filter unpublished content from public API responses
• Update admin CRUD controllers to show and toggle the published status

Part of #35