Update image URL handling and edit link in Event Themes

Replaced direct `preview_image_url` usage with `getServerFileUrl` for consistent file URL handling. Updated the "Edit Theme" button to navigate to the `/edit` path for improved routing clarity.

frontend/src/app/(main)/dashboard/event-themes/page.tsx

@@ -16,6 +16,7 @@ import Image from "next/image";
 import Link from "next/link";
 import { Loader2Icon, PaletteIcon } from "lucide-react";
 import { useEventThemes } from "@/context/event-theme-context";
+import { getServerFileUrl } from "@/lib/utils";
 
 export default function EventThemesPage() {
   // const { data: themes, isLoading } = useQuery({
@@ -69,7 +70,7 @@ export default function EventThemesPage() {
               <CardHeader className="p-0 relative h-48 bg-gray-50 dark:bg-gray-800">
                 {theme.preview_image_url ? (
                   <Image
-                    src={theme.preview_image_url}
+                    src={getServerFileUrl(theme.preview_image_url) || ""}
                     alt={`${theme.name} Preview`}
                     style={{ objectFit: "cover" }}
                     fill
@@ -96,7 +97,7 @@ export default function EventThemesPage() {
                   )}
                 </div>
                 <Button variant="outline" size="sm" asChild className="w-full">
-                  <Link href={`/dashboard/event-themes/${theme.id}`}>
+                  <Link href={`/dashboard/event-themes/${theme.id}/edit`}>
                     Edit Theme
                   </Link>
                 </Button>