feat(life): add comments and replies to life posts

Introduce life_post_comments table for nested comment threads
Add API endpoints to create, reply to, and delete comments
Implement frontend UI with engagement counts and collapsible threads

frontend/src/i18n.ts

@@ -229,6 +229,26 @@ const messages = {
         composerPrompt: 'What would you like to share?',
         bodyLabel: 'Post',
         bodyPlaceholder: 'Share a thought, tip, or discovery...',
+        comments: 'Comments',
+        commentsCount: '{count} comments',
+        comment: 'Comment',
+        hideComments: 'Hide comments',
+        commentPlaceholder: 'Write a comment...',
+        commentReplyPlaceholder: 'Write a reply...',
+        postComment: 'Post comment',
+        postingComment: 'Posting comment',
+        reply: 'Reply',
+        postReply: 'Post reply',
+        postingReply: 'Posting reply',
+        cancelReply: 'Cancel reply',
+        noComments: 'No comments yet',
+        deleteComment: 'Delete comment',
+        deleteCommentConfirm: 'Delete this comment?',
+        commentDeleted: 'Comment deleted',
+        commentRequired: 'Please enter a comment.',
+        commentFailed: 'Comment failed',
+        replyFailed: 'Reply failed',
+        deleteCommentFailed: 'Delete comment failed',
         publish: 'Post',
         publishing: 'Posting',
         update: 'Update',
@@ -542,6 +562,26 @@ const messages = {
         composerPrompt: '想分享什么？',
         bodyLabel: '动态内容',
         bodyPlaceholder: '分享一段想法、心得或发现……',
+        comments: '评论',
+        commentsCount: '{count} 条评论',
+        comment: '评论',
+        hideComments: '收起评论',
+        commentPlaceholder: '写下评论……',
+        commentReplyPlaceholder: '写下回复……',
+        postComment: '发表评论',
+        postingComment: '评论中',
+        reply: '回复',
+        postReply: '发布回复',
+        postingReply: '回复中',
+        cancelReply: '取消回复',
+        noComments: '暂无评论',
+        deleteComment: '删除评论',
+        deleteCommentConfirm: '确认删除这条评论？',
+        commentDeleted: '评论已删除',
+        commentRequired: '请输入评论内容。',
+        commentFailed: '评论失败',
+        replyFailed: '回复失败',
+        deleteCommentFailed: '删除评论失败',
         publish: '发布',
         publishing: '发布中',
         update: '更新',