feat: Refactor template handling, improve scheduler functions, and add timezone utilities

- Moved Jinja2 template setup to a shared configuration file (templates_config.py) for consistent usage across routers.
- Introduced timezone utilities in a new module (timezone.py) to handle UTC to local time conversions and formatting.
- Updated all relevant routers to use the new shared template configuration and timezone filters.
- Enhanced templates to utilize local time formatting for various datetime fields, improving user experience with timezone awareness.

templates/partials/projects/assignment_list.html

@@ -10,7 +10,7 @@
                             <p class="text-xs text-gray-500 dark:text-gray-400 mt-1">Location: {{ item.location.name }}</p>
                         {% endif %}
                         <p class="text-xs text-gray-500 dark:text-gray-400 mt-1">
-                            Assigned: {% if item.assignment.assigned_at %}{{ item.assignment.assigned_at.strftime('%Y-%m-%d %H:%M') }}{% else %}Unknown{% endif %}
+                            Assigned: {% if item.assignment.assigned_at %}{{ item.assignment.assigned_at|local_datetime }}{% else %}Unknown{% endif %}
                         </p>
                     </div>
                     <button onclick="unassignUnit('{{ item.assignment.id }}')" class="text-xs px-3 py-1 rounded-full bg-amber-100 text-amber-800 dark:bg-amber-900/30 dark:text-amber-300">