feat: async chapter-names AI generation with review & apply

- Add POST /api/admin/text-gen/chapter-names/async backend endpoint: fire-and-forget,
  returns job_id immediately (HTTP 202), runs batch generation in background goroutine,
  persists proposed titles in ai_job payload when done
- Register new route in server.go alongside existing SSE endpoint (backward compat)
- Add SvelteKit proxy at /api/admin/text-gen/chapter-names/async
- Add SvelteKit proxy for GET /api/admin/ai-jobs/[id] (job detail with payload)
- Add Review button on ai-jobs page for done chapter-names jobs; inline panel shows
  editable title table (old to new) with Apply All button that POSTs to chapter-names/apply

ui/src/routes/api/admin/ai-jobs/[id]/+server.ts

@@ -0,0 +1,31 @@
+/**
+ * GET /api/admin/ai-jobs/[id]
+ *
+ * Admin-only proxy to the Go backend's AI job detail endpoint.
+ * Returns the full job record including the payload field (which contains
+ * results for completed chapter-names jobs).
+ */
+
+import { json, error } from '@sveltejs/kit';
+import type { RequestHandler } from './$types';
+import { log } from '$lib/server/logger';
+import { backendFetch } from '$lib/server/scraper';
+
+export const GET: RequestHandler = async ({ params, locals }) => {
+	if (!locals.user || locals.user.role !== 'admin') {
+		throw error(403, 'Forbidden');
+	}
+
+	const { id } = params;
+
+	let res: Response;
+	try {
+		res = await backendFetch(`/api/admin/ai-jobs/${id}`, { method: 'GET' });
+	} catch (e) {
+		log.error('admin/ai-jobs/get', 'backend proxy error', { id, err: String(e) });
+		throw error(502, 'Could not reach backend');
+	}
+
+	const data = await res.json().catch(() => ({}));
+	return json(data, { status: res.status });
+};

ui/src/routes/api/admin/text-gen/chapter-names/async/+server.ts

@@ -0,0 +1,35 @@
+/**
+ * POST /api/admin/text-gen/chapter-names/async
+ *
+ * Fire-and-forget variant: forwards to the Go backend's async endpoint and
+ * returns {job_id} immediately (HTTP 202). The backend runs generation in the
+ * background; the client polls GET /api/admin/ai-jobs/{id} for progress and
+ * then reviews/applies via POST /api/admin/text-gen/chapter-names/apply.
+ */
+
+import { json, error } from '@sveltejs/kit';
+import type { RequestHandler } from './$types';
+import { log } from '$lib/server/logger';
+import { backendFetch } from '$lib/server/scraper';
+
+export const POST: RequestHandler = async ({ request, locals }) => {
+	if (!locals.user || locals.user.role !== 'admin') {
+		throw error(403, 'Forbidden');
+	}
+
+	const body = await request.text();
+	let res: Response;
+	try {
+		res = await backendFetch('/api/admin/text-gen/chapter-names/async', {
+			method: 'POST',
+			headers: { 'content-type': 'application/json' },
+			body
+		});
+	} catch (e) {
+		log.error('admin/text-gen/chapter-names/async', 'backend proxy error', { err: String(e) });
+		throw error(502, 'Could not reach backend');
+	}
+
+	const data = await res.json().catch(() => ({}));
+	return json(data, { status: res.status });
+};