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/en/tasks.json

@@ -23,7 +23,8 @@
     "attachments": "Attachments",
     "comments": "Comments",
     "watchers": "Watchers",
-    "blockers": "Blockers"
+    "blockers": "Blockers",
+    "hours": "{{count}} hours"
   },
   "status": {
     "todo": "To Do",
@@ -31,7 +32,11 @@
     "review": "In Review",
     "done": "Done",
     "cancelled": "Cancelled",
-    "blocked": "Blocked"
+    "blocked": "Blocked",
+    "noStatus": "No Status",
+    "unassigned": "Unassigned",
+    "noDueDate": "No due date",
+    "notEstimated": "Not estimated"
   },
   "priority": {
     "low": "Low",
@@ -86,17 +91,32 @@
     "add": "Add Subtask",
     "placeholder": "Enter subtask title",
     "completed": "{{count}} / {{total}} completed",
-    "empty": "No subtasks"
+    "count": "{{count}} subtask(s)",
+    "empty": "No subtasks",
+    "adding": "Adding...",
+    "error": {
+      "load": "Failed to load subtasks",
+      "create": "Failed to create subtask"
+    }
   },
   "comments": {
     "title": "Comments",
-    "add": "Add Comment",
-    "placeholder": "Write your comment...",
+    "add": "Post Comment",
+    "placeholder": "Add a comment... Use @name to mention someone",
     "edited": "edited",
     "delete": "Delete Comment",
-    "confirmDelete": "Are you sure you want to delete this comment?",
+    "confirmDelete": "Are you sure you want to delete this comment? This action cannot be undone.",
     "empty": "No comments yet",
-    "reply": "Reply"
+    "reply": "Reply",
+    "mentioned": "Mentioned",
+    "replyingTo": "Replying to comment",
+    "posting": "Posting...",
+    "error": {
+      "load": "Failed to load comments",
+      "post": "Failed to post comment",
+      "update": "Failed to update comment",
+      "delete": "Failed to delete comment"
+    }
   },
   "attachments": {
     "title": "Attachments",
@@ -113,7 +133,26 @@
     "blockedBy": "Blocked by",
     "blocking": "Blocking",
     "remove": "Remove blocker",
-    "empty": "No blockers"
+    "empty": "No blockers",
+    "taskBlocked": "Task Blocked",
+    "markAsBlocked": "Mark as Blocked",
+    "activeBlocker": "Active Blocker",
+    "reportedBy": "Reported by",
+    "on": "on",
+    "resolutionNote": "Resolution Note",
+    "resolutionPlaceholder": "Describe how the blocker was resolved...",
+    "resolving": "Resolving...",
+    "resolveBlocker": "Resolve Blocker",
+    "blockerReason": "Blocker Reason",
+    "reasonPlaceholder": "Describe what is blocking this task...",
+    "history": "Blocker History",
+    "reported": "Reported",
+    "resolved": "Resolved",
+    "error": {
+      "load": "Failed to load blockers",
+      "create": "Failed to create blocker",
+      "resolve": "Failed to resolve blocker"
+    }
   },
   "messages": {
     "created": "Task created",
@@ -126,6 +165,18 @@
     "attachmentUploaded": "Attachment uploaded",
     "confirmDelete": "Are you sure you want to delete this task? This action cannot be undone."
   },
+  "kanban": {
+    "dropHere": "Drop tasks here"
+  },
+  "calendar": {
+    "allAssignees": "All Assignees",
+    "allPriorities": "All Priorities",
+    "activeOnly": "Active Only",
+    "completedOnly": "Completed Only",
+    "clearFilters": "Clear Filters",
+    "overdue": "Overdue",
+    "completed": "Completed"
+  },
   "empty": {
     "title": "No Tasks",
     "description": "There are no tasks yet. Create your first task to get started!",