feat: add primary image functionality to AdventureImage model and update related components

frontend/src/lib/components/CardCarousel.svelte

@@ -9,7 +9,11 @@
 	let image_url: string | null = null;
 
 	$: adventure_images = adventures.flatMap((adventure) =>
-		adventure.images.map((image) => ({ image: image.image, adventure: adventure }))
+		adventure.images.map((image) => ({
+			image: image.image,
+			adventure: adventure,
+			is_primary: image.is_primary
+		}))
 	);
 
 	$: {
@@ -18,6 +22,19 @@
 		}
 	}
 
+	$: {
+		// sort so that any image in adventure_images .is_primary is first
+		adventure_images.sort((a, b) => {
+			if (a.is_primary && !b.is_primary) {
+				return -1;
+			} else if (!a.is_primary && b.is_primary) {
+				return 1;
+			} else {
+				return 0;
+			}
+		});
+	}
+
 	function changeSlide(direction: string) {
 		if (direction === 'next' && currentSlide < adventure_images.length - 1) {
 			currentSlide = currentSlide + 1;