feat(lists): add direct user invitation to shared lists and streamline live-sync indicator

frontend/src/lib/api.ts

@@ -11,6 +11,7 @@ import {
   PriorityLevel,
   SharedList,
   Space,
+  SpaceMember,
   SystemSettings,
   Team,
   TaskList,
@@ -517,6 +518,19 @@ export const api = {
     });
   },
 
+  async addSpaceMember(spaceId: string, target: { userId?: string; email?: string; role?: string }): Promise<SpaceMember> {
+    return request<SpaceMember>(`/api/v1/spaces/${spaceId}/members`, {
+      method: 'POST',
+      body: JSON.stringify(target),
+    });
+  },
+
+  async removeSpaceMember(spaceId: string, userId: string): Promise<void> {
+    await request(`/api/v1/spaces/${spaceId}/members/${userId}`, {
+      method: 'DELETE',
+    });
+  },
+
   async getSpaceLists(spaceId: string): Promise<SharedList[]> {
     const res = await request<SharedList[]>(`/api/v1/spaces/${spaceId}/lists`);
     return ensureArray(res).map((l) => ({