Add Road Trip Planner template with interactive map and trip management features

- Implemented a new HTML template for the Road Trip Planner.
- Integrated Leaflet.js for interactive mapping and routing.
- Added functionality for searching and selecting parks to include in a trip.
- Enabled drag-and-drop reordering of selected parks.
- Included trip optimization and route calculation features.
- Created a summary display for trip statistics.
- Added functionality to save trips and manage saved trips.
- Enhanced UI with responsive design and dark mode support.

parks/models/areas.py

@@ -15,4 +15,15 @@ class ParkArea(TrackedModel):
     slug = models.SlugField(max_length=255)
     description = models.TextField(blank=True)
     opening_date = models.DateField(null=True, blank=True)
-    closing_date = models
+    closing_date = models.DateField(null=True, blank=True)
+
+    def save(self, *args, **kwargs):
+        if not self.slug:
+            self.slug = slugify(self.name)
+        super().save(*args, **kwargs)
+
+    def __str__(self):
+        return self.name
+
+    class Meta:
+        unique_together = ('park', 'slug')