feat: animar apertura y cierre de grupos

Co-authored-by: aider (openrouter/openai/gpt-5) <aider@aider.chat>

apps/web/src/routes/app/groups/+page.svelte

@@ -2,6 +2,7 @@
   import TaskItem from "$lib/ui/data/TaskItem.svelte";
   import Card from "$lib/ui/layout/Card.svelte";
   import { onMount } from "svelte";
+  import { slide, fade } from "svelte/transition";
 
   type GroupItem = {
     id: string;
@@ -162,7 +163,9 @@
           <span class="badge warn">🙅‍♂️: {g.counts.unassigned}</span>
         </span>
       </summary>
-      <Card>
+      {#if isOpen(g.id)}
+        <div in:slide={{ duration: 180 }} out:slide={{ duration: 180 }}>
+          <Card in:fade={{ duration: 120 }} out:fade={{ duration: 120 }}>
             <ul class="list">
               {#each itemsByGroup[g.id] || [] as t (t.id)}
                 <TaskItem
@@ -179,6 +182,8 @@
               {/each}
             </ul>
           </Card>
+        </div>
+      {/if}
     </details>
   {/each}
 {/if}