feat(life): add search and move post composer to modal

Support searching life posts by content
Move post creation and editing to a modal dialog
Add search toolbar and update empty states

frontend/src/i18n.ts

@@ -229,6 +229,10 @@ const messages = {
         composerPrompt: 'What would you like to share?',
         bodyLabel: 'Post',
         bodyPlaceholder: 'Share a thought, tip, or discovery...',
+        newPost: 'New Post',
+        search: 'Search Life',
+        searchPlaceholder: 'Search post content...',
+        searchEmpty: 'No posts match your search',
         comments: 'Comments',
         commentsCount: '{count} comments',
         comment: 'Comment',
@@ -572,6 +576,10 @@ 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……',
+        newPost: 'New Post',
+        search: '搜索动态',
+        searchPlaceholder: '搜索动态内容……',
+        searchEmpty: '没有匹配的动态',
         comments: '评论',
         commentsCount: '{count} 条评论',
         comment: '评论',