feat(ui): highlight user mention in comments and commit messages

templates/base/head.tmpl

@@ -26,6 +26,7 @@
 			.ui.secondary.menu .dropdown.item > .menu { margin-top: 0; }
 		</style>
 	</noscript>
+	{{template "shared/user/mention_highlight" .}}
 	{{template "base/head_opengraph" .}}
 	{{template "base/head_style" .}}
 	{{template "custom/header" .}}

templates/shared/user/mention_highlight.tmpl

@@ -0,0 +1,14 @@
+{{if .IsSigned}}
+	<style>
+		.comment,
+		.commit-summary,
+		.commit-body {
+			.mention[href="{{AppSubUrl}}/{{.SignedUser.Name}}" i] {
+				background-color: var(--color-primary-alpha-30);
+				color: var(--color-primary-dark-2);
+				border-radius: 5px;
+				padding: 1px 4px;
+			}
+		}
+	</style>
+{{end}}

tests/integration/mention_test.go

@@ -0,0 +1,21 @@
+// Copyright 2024 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package integration
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestHeadMentionCSS(t *testing.T) {
+	userSession := loginUser(t, "user2")
+	resp := userSession.MakeRequest(t, NewRequest(t, "GET", "/"), http.StatusOK)
+	assert.Contains(t, resp.Body.String(), `.mention[href="/user2" i]`)
+
+	guestSession := emptyTestSession(t)
+	resp = guestSession.MakeRequest(t, NewRequest(t, "GET", "/"), http.StatusOK)
+	assert.NotContains(t, resp.Body.String(), `.mention[href="`)
+}