perf: stream slow load functions in admin pages to unblock navigation

- image-gen, text-gen: books list streamed (listBooks is expensive on cold cache)
- ai-jobs: jobs list streamed; add 30s cache to listAIJobs (was uncached listAll)
- changelog: Gitea releases streamed on cold cache; cached path stays synchronous
- admin/+layout.svelte: remove duplicate audio/translation/image-gen nav links

ui/src/lib/server/pocketbase.ts

@@ -2287,10 +2287,17 @@ export async function getUserStats(
 
 // ─── AI Jobs ──────────────────────────────────────────────────────────────────
 
+const AI_JOBS_CACHE_KEY = 'admin:ai_jobs';
+const AI_JOBS_CACHE_TTL = 30; // 30 seconds — same as other admin job lists
+
 /**
  * List all AI jobs from PocketBase, sorted by started descending.
- * No caching — admin views always want fresh data.
+ * Short-lived cache (30s) to avoid hammering PocketBase on every navigation.
  */
 export async function listAIJobs(): Promise<AIJob[]> {
-	return listAll<AIJob>('ai_jobs', '', '-started');
+	const cached = await cache.get<AIJob[]>(AI_JOBS_CACHE_KEY);
+	if (cached) return cached;
+	const jobs = await listAll<AIJob>('ai_jobs', '', '-started');
+	await cache.set(AI_JOBS_CACHE_KEY, jobs, AI_JOBS_CACHE_TTL);
+	return jobs;
 }