Add test utilities and state machine diagrams for FSM models

- Introduced reusable test utilities in `backend/tests/utils` for FSM transitions, HTMX interactions, and common scenarios.
- Added factory functions for creating test submissions, parks, rides, and photo submissions.
- Implemented assertion helpers for verifying state changes, toast notifications, and transition logs.
- Created comprehensive state machine diagrams for all FSM-enabled models in `docs/STATE_DIAGRAMS.md`, detailing states, transitions, and guard conditions.

backend/apps/rides/views.py

@@ -35,6 +35,33 @@ def show_coaster_fields(request: HttpRequest) -> HttpResponse:
     return render(request, "rides/partials/coaster_fields.html")
 
 
+def ride_status_actions(request: HttpRequest, park_slug: str, ride_slug: str) -> HttpResponse:
+    """Return FSM status actions for ride moderators"""
+    park = get_object_or_404(Park, slug=park_slug)
+    ride = get_object_or_404(Ride, park=park, slug=ride_slug)
+
+    # Only show to moderators
+    if not request.user.has_perm('rides.change_ride'):
+        return HttpResponse("")
+
+    return render(request, "rides/partials/ride_status_actions.html", {
+        "ride": ride,
+        "park": park,
+        "user": request.user
+    })
+
+
+def ride_header_badge(request: HttpRequest, park_slug: str, ride_slug: str) -> HttpResponse:
+    """Return the header status badge partial for a ride"""
+    park = get_object_or_404(Park, slug=park_slug)
+    ride = get_object_or_404(Ride, park=park, slug=ride_slug)
+    return render(request, "rides/partials/ride_header_badge.html", {
+        "ride": ride,
+        "park": park,
+        "user": request.user
+    })
+
+
 class RideDetailView(HistoryMixin, DetailView):
     """View for displaying ride details"""