feat(tasks): refine enhanced task linking, outliner badge positioning, completion sync and unlink behavior

frontend/src/lib/api.ts

@@ -664,6 +664,12 @@ export const api = {
     });
   },
 
+  async unlinkEnhancedTask(taskId: string): Promise<{ unlinked: boolean }> {
+    return request<{ unlinked: boolean }>(`/api/v1/tasks/${encodeURIComponent(taskId)}/unlink`, {
+      method: 'POST',
+    });
+  },
+
   // --- DOCUMENT SHARING ---
   async getDocShares(docId: string): Promise<DocShare[]> {
     const res = await request<DocShare[]>(`/api/v1/documents/${docId}/shares`);