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/routes/admin/text-gen/+page.server.ts

@@ -1,5 +1,5 @@
 import type { PageServerLoad } from './$types';
-import { backendFetch } from '$lib/server/scraper';
+import { listTextModels } from '$lib/server/scraper';
 import { log } from '$lib/server/logger';
 import { listBooks } from '$lib/server/pocketbase';
 
@@ -18,23 +18,18 @@ export interface TextModelInfo {
 
 export const load: PageServerLoad = async () => {
 	// Parent layout already guards admin role.
-	const [modelsResult, books] = await Promise.allSettled([
-		(async () => {
-			const res = await backendFetch('/api/admin/text-gen/models');
-			if (!res.ok) throw new Error(`status ${res.status}`);
-			const data = await res.json();
-			return (data.models ?? []) as TextModelInfo[];
-		})(),
+	const [models, booksResult] = await Promise.allSettled([
+		listTextModels<TextModelInfo>(),
 		listBooks()
 	]);
 
-	if (modelsResult.status === 'rejected') {
-		log.warn('admin/text-gen', 'failed to load models', { err: String(modelsResult.reason) });
+	if (models.status === 'rejected') {
+		log.warn('admin/text-gen', 'failed to load models', { err: String(models.reason) });
 	}
 
 	return {
-		models: modelsResult.status === 'fulfilled' ? modelsResult.value : ([] as TextModelInfo[]),
-		books: (books.status === 'fulfilled' ? books.value : []).map((b) => ({
+		models: models.status === 'fulfilled' ? models.value : ([] as TextModelInfo[]),
+		books: (booksResult.status === 'fulfilled' ? booksResult.value : []).map((b) => ({
 			slug: b.slug,
 			title: b.title
 		})) as BookSummary[]