feat(admin): export full cluster volume list as JSON (#9876)

Adds an "Export All (JSON)" button on the Cluster Volumes page that pulls
the whole cluster's volume list from the master in one call, a superset of
volume.list. Beyond the table columns it carries garbage and fullness
ratios, modified time, compact revision, remote tiering keys, per-disk
capacity counts, EC shard sizes with file/delete counts, and a cluster-wide
duplicate-volume-id scan. Honors the active collection filter. The existing
per-page CSV export stays as "Export Page".

weed/admin/static/js/admin.js

@@ -736,6 +736,18 @@ function exportVolumes() {
     downloadCSV(csv, 'seaweedfs-volumes.csv');
 }
 
+// Export the full cluster volume list (all volumes + EC shards, more fields than
+// the table) as a JSON report served by the admin API. Carries the active
+// collection filter from the page URL.
+function exportVolumeList() {
+    let url = basePath('/api/volumes/export');
+    const collection = new URLSearchParams(window.location.search).get('collection');
+    if (collection) {
+        url += '?collection=' + encodeURIComponent(collection);
+    }
+    window.open(url, '_blank');
+}
+
 // Export collections data as CSV
 function exportCollections() {
     const table = document.getElementById('collectionsTable');