fix: restore broken getSummary function declaration

Co-Authored-By: Claude <noreply@anthropic.com>

src/lib/proxmox.js

@@ -177,6 +177,9 @@ export async function powerControl(nodeName, vmid, type, action) {
 
 /**
  * Aggregated summary across all nodes.
+ * @returns {Promise<SummaryStat>}
+ */
+export async function getSummary() {
   const nodes = await getNodes();
   let totalVMs = [];
   let totalLXC = [];