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/templates/components/status_badge.html

@@ -1,17 +1,22 @@
 {% comment %}
 Reusable status badge component with consistent styling.
 Usage: {% include 'components/status_badge.html' with status="OPERATING" %}
+Usage (clickable): {% include 'components/status_badge.html' with status="OPERATING" clickable=True %}
 {% endcomment %}
 
 {% load park_tags %}
 
 {% with status_config=status|get_status_config %}
-<span class="inline-flex items-center px-2.5 py-0.5 rounded-full text-xs font-medium {{ status_config.classes }}">
+<span class="inline-flex items-center px-2.5 py-0.5 rounded-full text-xs font-medium {{ status_config.classes }}
+             {% if clickable %}cursor-pointer transition-all hover:ring-2 hover:ring-blue-500{% endif %}">
     {% if status_config.icon %}
     <svg class="-ml-0.5 mr-1.5 h-2 w-2" fill="currentColor" viewBox="0 0 8 8">
         <circle cx="4" cy="4" r="3" />
     </svg>
     {% endif %}
     {{ status_config.label }}
+    {% if clickable %}
+    <i class="fas fa-chevron-down ml-1.5 text-xs"></i>
+    {% endif %}
 </span>
 {% endwith %}