feat: complete i18n translation for remaining components

- Translate pages: Projects, ProjectHealthPage, ProjectSettings
- Translate components: TaskDetailModal, KanbanBoard, Comments,
  SubtaskList, CalendarView, BlockerDialog
- Add translation keys for tasks namespace: kanban, calendar,
  subtasks.error, comments.error, blockers (full translation)
- Add common.labels.task translation key
- Fix task creation: use original_estimate instead of time_estimate

Translation coverage:
- 10 locale files updated (zh-TW & en)
- 6 page/component files translated
- ~100 new translation keys added

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/pages/Tasks.tsx

@@ -322,7 +322,7 @@ export default function Tasks() {
         payload.due_date = newTask.due_date
       }
       if (newTask.time_estimate) {
-        payload.time_estimate = Number(newTask.time_estimate)
+        payload.original_estimate = Number(newTask.time_estimate)
       }
 
       // Include custom field values (only non-formula fields)