feat(time-tracking) : add TimeEntry DTO, service, timer store, and i18n keys

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

frontend/services/dto/task.ts

@@ -4,6 +4,7 @@ import type { TaskPriority } from './task-priority'
 import type { TaskType } from './task-type'
 import type { TaskGroup } from './task-group'
 import type { UserData } from './user-data'
+import type { Project } from './project'
 
 export type Task = {
     id: number
@@ -15,6 +16,7 @@ export type Task = {
     priority: TaskPriority | null
     assignee: UserData | null
     group: TaskGroup | null
+    project: Project | null
     types: TaskType[]
 }