feat: task management enhancements (cancelled status, recurrence, timestamps)

- Add 'cancelled' status to TaskStatus type, StatusBadge, TaskCard,
  TaskEditorView, TaskViewerView, TasksListView
- Add RecurrenceEditor component (none / interval / calendar rules)
- TaskEditorView: wire RecurrenceEditor, show started_at/completed_at
  timestamps read-only, include recurrence_rule in save payload
- TaskViewerView: show recurrence summary, timestamps in meta row
- tasks.ts: statusFilter/priorityFilter as arrays, add recurrence_rule
  to updateTask and createTask payloads

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/stores/tasks.ts

@@ -12,8 +12,8 @@ export const useTasksStore = defineStore("tasks", () => {
 
   // Filter / pagination / sort state
   const activeTagFilters = ref<string[]>([]);
-  const statusFilter = ref<TaskStatus | "">("");
-  const priorityFilter = ref<TaskPriority | "">("");
+  const statusFilter = ref<TaskStatus[]>([]);
+  const priorityFilter = ref<TaskPriority[]>([]);
   const limit = ref(20);
   const offset = ref(0);
   const sortField = ref("updated_at");
@@ -28,9 +28,8 @@ export const useTasksStore = defineStore("tasks", () => {
       for (const t of activeTagFilters.value) {
         searchParams.append("tag", t);
       }
-      if (statusFilter.value) searchParams.set("status", statusFilter.value);
-      if (priorityFilter.value)
-        searchParams.set("priority", priorityFilter.value);
+      for (const s of statusFilter.value) searchParams.append("status", s);
+      for (const p of priorityFilter.value) searchParams.append("priority", p);
       searchParams.set("sort", sortField.value);
       searchParams.set("order", sortOrder.value);
       searchParams.set("limit", String(limit.value));
@@ -72,6 +71,7 @@ export const useTasksStore = defineStore("tasks", () => {
     project_id?: number | null;
     milestone_id?: number | null;
     parent_id?: number | null;
+    recurrence_rule?: Record<string, unknown> | null;
   }): Promise<Task> {
     try {
       return await apiPost<Task>("/api/tasks", data);
@@ -84,7 +84,7 @@ export const useTasksStore = defineStore("tasks", () => {
   async function updateTask(
     id: number,
     data: Partial<
-      Pick<Task, "title" | "body" | "tags" | "status" | "priority" | "due_date" | "project_id" | "milestone_id" | "parent_id">
+      Pick<Task, "title" | "body" | "tags" | "status" | "priority" | "due_date" | "project_id" | "milestone_id" | "parent_id" | "recurrence_rule">
     >
   ): Promise<Task> {
     try {
@@ -129,14 +129,14 @@ export const useTasksStore = defineStore("tasks", () => {
     }
   }
 
-  function setStatusFilter(status: TaskStatus | "") {
-    statusFilter.value = status;
+  function setStatusFilter(statuses: TaskStatus[]) {
+    statusFilter.value = statuses;
     offset.value = 0;
     refresh();
   }
 
-  function setPriorityFilter(priority: TaskPriority | "") {
-    priorityFilter.value = priority;
+  function setPriorityFilter(priorities: TaskPriority[]) {
+    priorityFilter.value = priorities;
     offset.value = 0;
     refresh();
   }