Refactor frontend tw-justify-between layouts to flex-left-right (#37291)

This PR standardizes left/right two-child frontend layouts on
`flex-left-right` and removes ad-hoc `tw-justify-between` combinations.
The goal is consistent wrapping + spacing behavior under narrow widths
with less utility-class churn.

Also: remove useless "flex-center-wrap", slightly improve some templates
(no visual change, tested)

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: wxiaoguang <2114189+wxiaoguang@users.noreply.github.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

templates/repo/issue/view_content/conversation.tmpl

@@ -11,7 +11,7 @@ The variables in "ctx.Data" are different in each case, making this template fra
 	{{$hasReview := and $comment.Review}}
 	{{$isReviewPending := and $hasReview (eq $comment.Review.Type 0)}}
 	<div class="ui segments conversation-holder">
-		<div class="ui segment collapsible-comment-box tw-py-2 tw-flex tw-items-center tw-justify-between">
+		<div class="ui segment collapsible-comment-box tw-py-2 flex-left-right">
 			<div class="tw-flex tw-items-center">
 				<a href="{{$comment.CodeCommentLink ctx}}" class="file-comment tw-ml-2 tw-break-anywhere">{{$comment.TreePath}}</a>
 				{{if $invalid}}