chore: streamline the URL used for resources like favicon.png

src/routes/auth/+page.svelte

@@ -123,10 +123,10 @@
 
 			if (isDarkMode) {
 				const darkImage = new Image();
-				darkImage.src = '/static/favicon-dark.png';
+				darkImage.src = `${WEBUI_BASE_URL}/static/favicon-dark.png`;
 
 				darkImage.onload = () => {
-					logo.src = '/static/favicon-dark.png';
+					logo.src = `${WEBUI_BASE_URL}/static/favicon-dark.png`;
 					logo.style.filter = ''; // Ensure no inversion is applied if favicon-dark.png exists
 				};