修复帖内 CSS 污染整页：前后端禁止 style 并消毒 HTML。

Co-authored-by: Cursor <cursoragent@cursor.com>

service/sanitize_html_test.go

@@ -0,0 +1,57 @@
+package service
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestSanitizePostHTML_StripsStyleLeak(t *testing.T) {
+	in := "<center>你好</center>\n<style>\n* {color:red}\n</style>"
+	out := SanitizePostHTML(in)
+	if strings.Contains(strings.ToLower(out), "<style") {
+		t.Fatalf("应剥离 style 标签，得到: %q", out)
+	}
+	if strings.Contains(out, "color:red") {
+		t.Fatalf("不应保留 CSS 文本，得到: %q", out)
+	}
+	if !strings.Contains(out, "你好") {
+		t.Fatalf("应保留正文，得到: %q", out)
+	}
+}
+
+func TestSanitizePostHTML_StripsInlineStyleAndScript(t *testing.T) {
+	in := `<p style="color:red">段落</p><script>alert(1)</script><img src="/uploads/posts/a.jpg" data-display="wide" class="article-img">`
+	out := SanitizePostHTML(in)
+	if strings.Contains(strings.ToLower(out), "style=") {
+		t.Fatalf("应剥离 style 属性，得到: %q", out)
+	}
+	if strings.Contains(strings.ToLower(out), "<script") {
+		t.Fatalf("应剥离 script，得到: %q", out)
+	}
+	if !strings.Contains(out, "data-display") {
+		t.Fatalf("应保留 data-display，得到: %q", out)
+	}
+}
+
+func TestSanitizePostHTML_KeepsMembersOnlyAndImageGroup(t *testing.T) {
+	in := `<members-only data-locked="false"><p>密</p></members-only>` +
+		`<div data-image-group data-layout="cols-2" class="image-group"><img src="/uploads/posts/a.jpg" alt="x"></div>` +
+		`<p data-clear-float class="article-clear-float">清浮动</p>`
+	out := SanitizePostHTML(in)
+	for _, want := range []string{"members-only", "data-image-group", "data-layout", "data-clear-float", "清浮动"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("缺少 %q，得到: %q", want, out)
+		}
+	}
+}
+
+func TestStripHTMLForSearch_DropsStyleText(t *testing.T) {
+	in := "<center>你好</center><style>* {color:red}</style>"
+	out := StripHTMLForSearch(in)
+	if strings.Contains(out, "color") || strings.Contains(out, "red") {
+		t.Fatalf("摘要不应含 CSS，得到: %q", out)
+	}
+	if out != "你好" {
+		t.Fatalf("期望 %q，得到 %q", "你好", out)
+	}
+}