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/moderation/urls.py

@@ -7,6 +7,7 @@ moderation functionality including reports, queue management, actions, and bulk
 """
 
 from django.urls import path, include
+from django.views.generic import TemplateView
 from rest_framework.routers import DefaultRouter
 
 from .views import (
@@ -16,6 +17,49 @@ from .views import (
     BulkOperationViewSet,
     UserModerationViewSet,
 )
+from apps.core.views.views import FSMTransitionView
+
+
+class ModerationDashboardView(TemplateView):
+    """Moderation dashboard view with HTMX integration."""
+    template_name = "moderation/dashboard.html"
+
+    def get_context_data(self, **kwargs):
+        from .models import EditSubmission, PhotoSubmission
+        from .selectors import pending_submissions_for_review
+
+        context = super().get_context_data(**kwargs)
+        context["submissions"] = pending_submissions_for_review()
+        return context
+
+
+class SubmissionListView(TemplateView):
+    """Submission list view with filtering."""
+    template_name = "moderation/partials/dashboard_content.html"
+
+    def get_context_data(self, **kwargs):
+        from .models import EditSubmission, PhotoSubmission
+        from itertools import chain
+
+        context = super().get_context_data(**kwargs)
+        status = self.request.GET.get("status", "PENDING")
+
+        # Get filtered submissions
+        edit_submissions = EditSubmission.objects.filter(status=status).select_related("user")
+        photo_submissions = PhotoSubmission.objects.filter(status=status).select_related("user")
+
+        # Combine and sort
+        context["submissions"] = sorted(
+            chain(edit_submissions, photo_submissions),
+            key=lambda x: x.created_at,
+            reverse=True,
+        )
+        return context
+
+
+class HistoryPageView(TemplateView):
+    """Main history page view."""
+    template_name = "moderation/history.html"
 
 # Create router and register viewsets
 router = DefaultRouter()
@@ -27,11 +71,104 @@ router.register(r"users", UserModerationViewSet, basename="user-moderation")
 
 app_name = "moderation"
 
-urlpatterns = [
-    # Include all router URLs
-    path("", include(router.urls)),
+# FSM transition convenience URLs for moderation models
+fsm_transition_patterns = [
+    # EditSubmission transitions
+    # URL: /api/moderation/submissions/<pk>/transition/<transition_name>/
+    path(
+        "submissions/<int:pk>/transition/<str:transition_name>/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "editsubmission"},
+        name="submission_transition",
+    ),
+    # PhotoSubmission transitions
+    # URL: /api/moderation/photos/<pk>/transition/<transition_name>/
+    path(
+        "photos/<int:pk>/transition/<str:transition_name>/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "photosubmission"},
+        name="photo_transition",
+    ),
+    # ModerationReport transitions
+    # URL: /api/moderation/reports/<pk>/transition/<transition_name>/
+    path(
+        "reports/<int:pk>/transition/<str:transition_name>/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "moderationreport"},
+        name="report_transition",
+    ),
+    # ModerationQueue transitions
+    # URL: /api/moderation/queue/<pk>/transition/<transition_name>/
+    path(
+        "queue/<int:pk>/transition/<str:transition_name>/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "moderationqueue"},
+        name="queue_transition",
+    ),
+    # BulkOperation transitions
+    # URL: /api/moderation/bulk/<pk>/transition/<transition_name>/
+    path(
+        "bulk/<int:pk>/transition/<str:transition_name>/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "bulkoperation"},
+        name="bulk_operation_transition",
+    ),
+    # Backward compatibility aliases for EditSubmission actions
+    # These redirect the old URL patterns to the FSM transition view
+    path(
+        "submissions/<int:pk>/approve/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "editsubmission", "transition_name": "transition_to_approved"},
+        name="approve_submission",
+    ),
+    path(
+        "submissions/<int:pk>/reject/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "editsubmission", "transition_name": "transition_to_rejected"},
+        name="reject_submission",
+    ),
+    path(
+        "submissions/<int:pk>/escalate/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "editsubmission", "transition_name": "transition_to_escalated"},
+        name="escalate_submission",
+    ),
+    # Backward compatibility aliases for PhotoSubmission actions
+    path(
+        "photos/<int:pk>/approve/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "photosubmission", "transition_name": "transition_to_approved"},
+        name="approve_photo",
+    ),
+    path(
+        "photos/<int:pk>/reject/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "photosubmission", "transition_name": "transition_to_rejected"},
+        name="reject_photo",
+    ),
+    path(
+        "photos/<int:pk>/escalate/",
+        FSMTransitionView.as_view(),
+        {"app_label": "moderation", "model_name": "photosubmission", "transition_name": "transition_to_escalated"},
+        name="escalate_photo",
+    ),
 ]
 
+# HTML page patterns (for moderation dashboard)
+html_patterns = [
+    path("", ModerationDashboardView.as_view(), name="dashboard"),
+    path("submissions/", SubmissionListView.as_view(), name="submission_list"),
+    path("history/", HistoryPageView.as_view(), name="history"),
+]
+
+urlpatterns = [
+    # HTML page views
+    *html_patterns,
+    # Include all router URLs (API endpoints)
+    path("api/", include(router.urls)),
+    # FSM transition convenience endpoints
+] + fsm_transition_patterns
+
 # URL patterns generated by the router:
 #
 # Moderation Reports: