feat: add AI Jobs admin page, cache model lists, improve image-gen 502 UX

- Add /admin/ai-jobs page with live-polling jobs table, status badges, progress bars, and cancel action
- Add listAIJobs() helper in pocketbase.ts; AIJob type
- Add POST /api/admin/ai-jobs/[id]/cancel SvelteKit proxy
- Add ai-jobs link to admin sidebar nav (all 5 locales)
- Cache image-gen and text-gen model lists in Valkey (10 min TTL) via scraper.ts helpers
- Cache changelog Gitea API response (5 min TTL)
- Improve 502/504 error message on image-gen page with CF AI timeout hint
- Show CF AI timeout warning in advanced options when a Cloudflare/FLUX model is selected

ui/src/lib/server/pocketbase.ts

@@ -14,6 +14,23 @@ const PB_PASSWORD = env.POCKETBASE_ADMIN_PASSWORD ?? 'changeme123';
 
 // ─── Types ────────────────────────────────────────────────────────────────────
 
+export interface AIJob {
+	id: string;
+	kind: string;
+	slug: string;
+	status: 'pending' | 'running' | 'done' | 'failed' | 'cancelled';
+	from_item: number;
+	to_item: number;
+	items_done: number;
+	items_total: number;
+	model: string;
+	payload: string;
+	error_message?: string;
+	started?: string;
+	finished?: string;
+	heartbeat_at?: string;
+}
+
 export interface Book {
 	id: string;
 	slug: string;
@@ -2162,3 +2179,13 @@ export async function getUserStats(
 		streak
 	};
 }
+
+// ─── AI Jobs ──────────────────────────────────────────────────────────────────
+
+/**
+ * List all AI jobs from PocketBase, sorted by started descending.
+ * No caching — admin views always want fresh data.
+ */
+export async function listAIJobs(): Promise<AIJob[]> {
+	return listAll<AIJob>('ai_jobs', '', '-started');
+}