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/org/team/sidebar.tmpl

@@ -1,7 +1,7 @@
 <div class="ui six wide column">
 	<h4 class="ui top attached header flex-left-right">
 		<strong>{{.Team.Name}}</strong>
-		<div class="flex-center-wrap">
+		<div class="flex-text-block">
 			{{if .Team.IsMember ctx $.SignedUser.ID}}
 				<button class="ui red mini compact button show-modal" data-modal="#org-member-leave-team"
 					data-modal-form.action="{{$.OrgLink}}/teams/{{$.Team.LowerName | PathEscape}}/action/leave?uid={{$.SignedUser.ID}}"