feat: implement media editing functionality in App component, enhance MediaFormModal for editing, and update MediaItem to trigger edit action

src/lib/MediaItem.svelte

@@ -1,8 +1,7 @@
 <script lang="ts">
-  import type { Media } from './interfaces';
   import { fade } from 'svelte/transition';
-
-  export let media: Media;
+  import type { Media } from './interfaces';
+  let {media, onEdit}: {media: Media, onEdit: (media: Media) => void} = $props();
 
   // 状态映射
   const statusMap = {
@@ -16,7 +15,7 @@
 </script>
 
 <div class="border rounded-lg p-4 hover:bg-gray-50" transition:fade>
-  <div class="flex justify-between items-start">
+  <div class="flex justify-between items-start" role="presentation" onclick={() => onEdit(media)}>
     <div class="space-y-2 flex-1">
       <div class="flex items-center justify-between">
         <h3 class="text-lg font-medium text-gray-900 truncate max-w-[70%]">{media.title}</h3>