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/public/locales/zh-TW/common.json

@@ -52,7 +52,8 @@
     "selectAssignee": "選擇負責人...",
     "searchUsers": "搜尋使用者...",
     "noUsersFound": "找不到使用者",
-    "typeToSearch": "輸入以搜尋使用者"
+    "typeToSearch": "輸入以搜尋使用者",
+    "task": "任務"
   },
   "messages": {
     "success": "操作成功",