feat(评论): 添加Markdown渲染和样式支持

- 引入marked和xss库处理评论内容的Markdown渲染和XSS过滤
- 添加CSS样式支持评论内容的标题、列表、代码块等Markdown元素显示

widget/src/styles/main.css

@@ -396,6 +396,101 @@
   text-decoration: underline;
 }
 
+.cwd-comment-content h1,
+.cwd-comment-content h2,
+.cwd-comment-content h3,
+.cwd-comment-content h4,
+.cwd-comment-content h5,
+.cwd-comment-content h6 {
+  margin-top: 16px;
+  margin-bottom: 8px;
+  font-weight: 600;
+  line-height: 1.25;
+}
+
+.cwd-comment-content h1 {
+  font-size: 1.5em;
+}
+
+.cwd-comment-content h2 {
+  font-size: 1.3em;
+}
+
+.cwd-comment-content h3 {
+  font-size: 1.1em;
+}
+
+.cwd-comment-content ul,
+.cwd-comment-content ol {
+  padding-left: 1.7em;
+  margin: 0 0 8px;
+}
+
+.cwd-comment-content li + li {
+  margin-top: 4px;
+}
+
+.cwd-comment-content code {
+  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
+  font-size: 0.9em;
+  background: var(--cwd-bg-secondary, #f6f8fa);
+  padding: 0.2em 0.4em;
+  border-radius: 4px;
+}
+
+.cwd-comment-content pre {
+  padding: 12px;
+  margin: 12px 0;
+  overflow-x: auto;
+  background: var(--cwd-bg-secondary, #f6f8fa);
+  border-radius: 6px;
+  font-size: 0.9em;
+}
+
+.cwd-comment-content pre code {
+  padding: 0;
+  background: transparent;
+  border-radius: 0;
+  display: block;
+}
+
+.cwd-comment-content blockquote {
+  margin: 8px 0;
+  padding: 0 12px;
+  border-left: 4px solid var(--cwd-border, #d0d7de);
+  color: var(--cwd-text-secondary, #6e7781);
+}
+
+.cwd-comment-content hr {
+  border: 0;
+  border-top: 1px solid var(--cwd-border-light, #eaeef2);
+  margin: 16px 0;
+}
+
+.cwd-comment-content table {
+  border-collapse: collapse;
+  border-spacing: 0;
+  width: 100%;
+  font-size: 13px;
+  margin: 12px 0;
+}
+
+.cwd-comment-content th,
+.cwd-comment-content td {
+  border: 1px solid var(--cwd-border, #d0d7de);
+  padding: 6px 12px;
+  text-align: left;
+}
+
+.cwd-comment-content th {
+  background: var(--cwd-bg-secondary, #f6f8fa);
+}
+
+.cwd-comment-content img {
+  max-width: 100%;
+  height: auto;
+}
+
 .cwd-comment-actions {
   display: flex;
   align-items: center;
@@ -617,4 +712,4 @@
 
 .cwd-comments-container::-webkit-scrollbar-thumb:hover {
   background: var(--cwd-text-secondary);
-}
+}