add vikunja integration

frontend/src/types/vikunja.types.ts

@@ -0,0 +1,23 @@
+export interface VikunjaTask {
+  id: number;
+  title: string;
+  done: boolean;
+  due_date: string | null;
+  priority: number;
+  project_id: number;
+}
+
+export interface VikunjaProject {
+  id: number;
+  title: string;
+}
+
+export interface VikunjaTasksResponse {
+  configured: boolean;
+  data: VikunjaTask[];
+}
+
+export interface VikunjaProjectsResponse {
+  configured: boolean;
+  data: VikunjaProject[];
+}