Default test-server selection to none on beta open

src/routes/betas/+page.svelte

@@ -113,7 +113,8 @@
         const eligibleVersions = detail.versions.filter((v) => v.id !== detail.script.current_version_id);
         pick.versionId = eligibleVersions[0]?.id ?? null;
         picks = [...picks];
-        pickedServers = new Set(candidateServers);
+        // Start with nothing selected — user opts in each server explicitly.
+        pickedServers = new Set();
     }
 
     function addRow(): void {
@@ -121,7 +122,8 @@
     }
     function removeRow(idx: number): void {
         picks = picks.filter((_, i) => i !== idx);
-        pickedServers = new Set(candidateServers);
+        // Start with nothing selected — user opts in each server explicitly.
+        pickedServers = new Set();
     }
     function toggleServer(name: string): void {
         const next = new Set(pickedServers);