Add GitHub plugin release imports and update discovery

src/routes/betas/+page.svelte

@@ -82,7 +82,7 @@
 
     let poll: ReturnType<typeof setInterval> | null = null;
     onMount(() => {
-        load();
+        void load().then(seedImportedPlugin).catch(error => { flash = (error as Error).message; });
         poll = setInterval(refreshBetas, 5000);
     });
     onDestroy(() => {
@@ -102,6 +102,26 @@
         return eligibleScripts.filter((s) => !takenIds.has(s.id));
     }
 
+    async function seedImportedPlugin(): Promise<void> {
+        const query = new URLSearchParams(window.location.search);
+        if (!query.has('pluginId')) return;
+        const pluginId = Number(query.get('pluginId'));
+        const versionId = Number(query.get('versionId'));
+        if (!eligibleScripts.some(s => s.id === pluginId && s.kind === 'plugin')) {
+            flash = 'This plugin is already promoted or has a running beta. Open its detail page to review its status.';
+            return;
+        }
+        picks = [{ key: nextKey++, scriptId: pluginId, versionId: null }];
+        await onPickScript(0);
+        if (!versionsForRow(picks[0]).some(v => v.id === versionId)) {
+            picks[0].versionId = null;
+            flash = 'The imported version is no longer available for testing. Choose a version to continue.';
+            return;
+        }
+        picks[0].versionId = versionId;
+        picks = [...picks];
+    }
+
     async function onPickScript(rowIdx: number): Promise<void> {
         flash = null;
         const pick = picks[rowIdx];