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/settings/webhook/history.tmpl

@@ -17,7 +17,7 @@
 		<div class="ui list">
 			{{range .History}}
 				<div class="item">
-					<div class="flex-text-block tw-justify-between">
+					<div class="flex-left-right">
 						<div class="flex-text-inline">
 							{{if .IsSucceed}}
 								<span class="tw-text-green">{{svg "octicon-check"}}</span>