fix: Fixes cursor handling for API link requests

Replaces the cursor value in the API request with `undefined` if it is falsy. This prevents potential issues with null values being sent in the query, ensuring a more reliable API interaction.

Improves overall stability when fetching link data from the server.

Author: ccbikai

components/dashboard/links/Index.vue

@@ -11,7 +11,7 @@ async function getLinks() {
   const data = await useAPI('/api/link/list', {
     query: {
       limit,
-      cursor,
+      cursor: cursor || undefined,
     },
   })
   links.value = links.value.concat(data.links).filter(Boolean) // Sometimes cloudflare will return null, filter out