fix(widget): 修复页面访问量获取失败的问题

- 前端 trackVisit 现在传递 siteId 参数
- 后端 getPagePv 查询时处理 site_id 为空或 NULL 的情况

cwd-api/src/api/public/getPagePv.ts

@@ -12,11 +12,23 @@ export const getPagePv = async (c: Context<{ Bindings: Bindings }>) => {
 			return c.json({ message: 'post_slug is required' }, 400);
 		}
 
-		const row = await c.env.CWD_DB.prepare(
-			'SELECT pv FROM page_stats WHERE post_slug = ? AND site_id = ?'
-		)
-			.bind(postSlug, siteId)
-			.first<{ pv: number }>();
+		let row: { pv: number } | null = null;
+
+		if (siteId) {
+			// 有 siteId 时精确匹配
+			row = await c.env.CWD_DB.prepare(
+				'SELECT pv FROM page_stats WHERE post_slug = ? AND site_id = ?'
+			)
+				.bind(postSlug, siteId)
+				.first<{ pv: number }>();
+		} else {
+			// 无 siteId 时，匹配空字符串或 NULL
+			row = await c.env.CWD_DB.prepare(
+				'SELECT pv FROM page_stats WHERE post_slug = ? AND (site_id = ? OR site_id IS NULL)'
+			)
+				.bind(postSlug, '')
+				.first<{ pv: number }>();
+		}
 
 		const pv = row?.pv || 0;