feat : add task management with kanban and backlog

Add kanban board with drag-and-drop, backlog section, task/group
drawers, DTOs, services, and i18n translations.

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

frontend/services/task-priorities.ts

@@ -0,0 +1,32 @@
+import type { TaskPriority, TaskPriorityWrite } from './dto/task-priority'
+import type { HydraCollection } from '~/utils/api'
+import { extractHydraMembers } from '~/utils/api'
+
+export function useTaskPriorityService() {
+    const api = useApi()
+
+    async function getAll(): Promise<TaskPriority[]> {
+        const data = await api.get<HydraCollection<TaskPriority>>('/task_priorities')
+        return extractHydraMembers(data)
+    }
+
+    async function create(payload: TaskPriorityWrite): Promise<TaskPriority> {
+        return api.post<TaskPriority>('/task_priorities', payload as Record<string, unknown>, {
+            toastSuccessKey: 'taskPriorities.created',
+        })
+    }
+
+    async function update(id: number, payload: Partial<TaskPriorityWrite>): Promise<TaskPriority> {
+        return api.patch<TaskPriority>(`/task_priorities/${id}`, payload as Record<string, unknown>, {
+            toastSuccessKey: 'taskPriorities.updated',
+        })
+    }
+
+    async function remove(id: number): Promise<void> {
+        await api.delete(`/task_priorities/${id}`, {}, {
+            toastSuccessKey: 'taskPriorities.deleted',
+        })
+    }
+
+    return { getAll, create, update, remove }
+}