Add admin badge to navbar avatar (#36790)

Replace the standalone site admin icon in the navbar with a
Discord-style shield badge on the user avatar.

<img width="278" height="73" alt="image"
src="https://github.com/user-attachments/assets/0b074006-30b9-43c6-8ef2-2120e32e139a"
/>


Fixes: https://github.com/go-gitea/gitea/issues/35904

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

templates/base/head_navbar.tmpl

@@ -87,8 +87,11 @@
 			</div><!-- end dropdown menu create new -->
 
 			<div class="ui dropdown jump item" data-tooltip-content="{{ctx.Locale.Tr "user_profile_and_more"}}">
-				<span class="text">
-					{{ctx.AvatarUtils.Avatar .SignedUser 24 "tw-mr-1"}}
+				<span class="text tw-flex tw-items-center">
+					<span class="navbar-avatar">
+						{{ctx.AvatarUtils.Avatar .SignedUser 24 "tw-mr-2"}}
+						{{if .IsAdmin}}{{svg "octicon-shield-check" 16 "navbar-admin-badge"}}{{end}}
+					</span>
 					<span class="only-mobile">{{.SignedUser.Name}}</span>
 					<span class="not-mobile">{{svg "octicon-triangle-down"}}</span>
 				</span>

templates/base/head_navbar_icons.tmpl

@@ -17,9 +17,4 @@
 			<span class="notification_count{{if not $notificationUnreadCount}} tw-hidden{{end}}">{{$notificationUnreadCount}}</span>
 		</div>
 	</a>
-	{{if $data.IsSiteAdmin}}
-	<a class="item {{$itemExtraClass}}" href="{{AppSubUrl}}/-/admin" data-tooltip-content="{{ctx.Locale.Tr "admin_panel"}}">
-		{{svg "octicon-server"}}
-	</a>
-	{{end}}
 {{end}}