feat: api health endpoint

[metaforx]

• /api/health -> returns 200

This would allow monitoring without needing users to add additional endpoints on their own.
It might be beneficial to add some minor test cases to check if CMS is properly up and running.

This would be a small improvement but would help integrate cms into monitoring without using custom endpoints.

Simple implementation

from django.http import JsonResponse

def health(request):
    return JsonResponse({"status": "ok"})

from django.urls import path
from .views import health

urlpatterns = [
    path("api/health/", health, name="api-health"),
]

@fsbraun What you think?