feat: implement comment reply system with nested support

- Add two-level nesting comment reply functionality
- Add replyToUserId field to track which user is being replied to
- Refresh comments immediately after reply submission
- Add numbering to comments and sort replies chronologically
- Move comment numbering to the left of timestamp
- Add type annotations to sort callback parameters
- Remove unused replyPrefix parameter from CommentItem
- Add database migration for reply functionality
- Update translation files for reply feature

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

Author: PBnicad

client/public/locales/en/translation.json

@@ -43,9 +43,12 @@
   "comment": {
     "empty": "Comment cannot be empty",
     "placeholder": {
-      "title": "Say something..."
+      "title": "Say something...",
+      "reply": "Reply..."
     },
+    "reply": "Reply",
     "submit": "Submit Comment",
+    "submitting": "Submitting...",
     "success": "Comment successful",
     "title": "Comment"
   },

client/public/locales/ja/translation.json

@@ -43,9 +43,12 @@
   "comment": {
     "empty": "コメント内容は空にできません",
     "placeholder": {
-      "title": "何か言ってください..."
+      "title": "何か言ってください...",
+      "reply": "返信..."
     },
+    "reply": "返信",
     "submit": "コメントを投稿",
+    "submitting": "投稿中...",
     "success": "コメントに成功しました",
     "title": "コメント"
   },

client/public/locales/zh-CN/translation.json

@@ -43,9 +43,12 @@
   "comment": {
     "empty": "评论内容不能为空",
     "placeholder": {
-      "title": "说点什么吧"
+      "title": "说点什么吧",
+      "reply": "回复..."
     },
+    "reply": "回复",
     "submit": "发表评论",
+    "submitting": "发表中...",
     "success": "评论成功",
     "title": "评论"
   },

client/public/locales/zh-TW/translation.json

@@ -43,9 +43,12 @@
   "comment": {
     "empty": "留言内容不能為空",
     "placeholder": {
-      "title": "說點什麼吧"
+      "title": "說點什麼吧",
+      "reply": "回覆..."
     },
+    "reply": "回覆",
     "submit": "發表留言",
+    "submitting": "發表中...",
     "success": "留言成功",
     "title": "留言"
   },