fix(admin): wrap plugin lane fetch URL with basePath

Plugin lane page fetches API endpoints with raw absolute URLs, breaking
deployments under a subdirectory. Wrap the fetch URL with basePath() so
window.__BASE_PATH__ is honored, matching other admin pages.

Addresses https://github.com/seaweedfs/seaweedfs/issues/9240

weed/admin/view/app/plugin_lane.templ

@@ -81,7 +81,7 @@ templ PluginLane(page string, lane string) {
         if (!lane) return;
 
         function fetchAndRender(url, containerId, renderFn) {
-            fetch(url)
+            fetch(basePath(url))
                 .then(r => r.json())
                 .then(data => {
                     const el = document.getElementById(containerId);