feat(ui): add structured JSON logging to all server-side routes and lib

Introduces a logger.ts module emitting slog-compatible JSON lines to stderr.
Replaces silent catch blocks and console.error calls throughout minio.ts,
pocketbase.ts, hooks.server.ts, login, books, browse, and all API routes so
auth/registration failures, MinIO presign errors, and scraper proxy failures
are now visible in container logs.

ui/src/routes/api/audio/[slug]/[n]/+server.ts

@@ -1,6 +1,7 @@
 import { error } from '@sveltejs/kit';
 import type { RequestHandler } from './$types';
 import { env } from '$env/dynamic/private';
+import { log } from '$lib/server/logger';
 
 const SCRAPER_URL = env.SCRAPER_API_URL ?? 'http://localhost:8080';
 
@@ -35,6 +36,7 @@ export const POST: RequestHandler = async ({ params, request }) => {
 
 	if (!scraperRes.ok) {
 		const text = await scraperRes.text().catch(() => '');
+		log.error('audio', 'scraper audio generation failed', { slug, chapter, status: scraperRes.status, body: text });
 		error(scraperRes.status as Parameters<typeof error>[0], text || 'Audio generation failed');
 	}
 
@@ -78,6 +80,7 @@ export const GET: RequestHandler = async ({ params, url }) => {
 	const scraperRes = await fetch(`${SCRAPER_URL}/api/audio-proxy/${slug}/${chapter}?${qs.toString()}`);
 
 	if (!scraperRes.ok) {
+		log.error('audio', 'scraper audio proxy failed', { slug, chapter, status: scraperRes.status });
 		error(scraperRes.status as Parameters<typeof error>[0], 'Audio not found');
 	}
 

ui/src/routes/api/presign/audio/+server.ts

@@ -1,6 +1,7 @@
 import { json, error } from '@sveltejs/kit';
 import type { RequestHandler } from './$types';
 import { presignAudio } from '$lib/server/minio';
+import { log } from '$lib/server/logger';
 
 /**
  * GET /api/presign/audio?slug=...&n=...&voice=...&speed=...
@@ -21,6 +22,7 @@ export const GET: RequestHandler = async ({ url }) => {
 		const presignedUrl = await presignAudio(slug, n, voice, speed);
 		return json({ url: presignedUrl });
 	} catch (e) {
+		log.error('presign', 'presign audio failed', { slug, n, err: String(e) });
 		error(500, `Could not get presigned URL: ${e}`);
 	}
 };

ui/src/routes/api/progress/+server.ts

@@ -1,6 +1,7 @@
 import { json, error } from '@sveltejs/kit';
 import type { RequestHandler } from './$types';
 import { setProgress } from '$lib/server/pocketbase';
+import { log } from '$lib/server/logger';
 
 /**
  * POST /api/progress
@@ -14,6 +15,11 @@ export const POST: RequestHandler = async ({ request, locals }) => {
 		error(400, 'Invalid body — expected { slug, chapter }');
 	}
 
-	await setProgress(locals.sessionId, body.slug, body.chapter);
+	try {
+		await setProgress(locals.sessionId, body.slug, body.chapter);
+	} catch (e) {
+		log.error('progress', 'setProgress failed', { slug: body.slug, chapter: body.chapter, err: String(e) });
+		error(500, 'Failed to save progress');
+	}
 	return json({ ok: true });
 };

ui/src/routes/api/scrape/+server.ts

@@ -18,6 +18,7 @@
 import { json, error } from '@sveltejs/kit';
 import type { RequestHandler } from './$types';
 import { env } from '$env/dynamic/private';
+import { log } from '$lib/server/logger';
 
 const SCRAPER_URL = env.SCRAPER_API_URL ?? 'http://localhost:8080';
 
@@ -39,11 +40,22 @@ export const POST: RequestHandler = async ({ request, locals }) => {
 	const endpoint = isBookScrape ? '/scrape/book' : '/scrape';
 
 	const upstream = `${SCRAPER_URL}${endpoint}`;
-	const res = await fetch(upstream, {
-		method: 'POST',
-		headers: { 'Content-Type': 'application/json' },
-		body: isBookScrape ? JSON.stringify({ url: body.url }) : undefined
-	});
+	let res: Response;
+	try {
+		res = await fetch(upstream, {
+			method: 'POST',
+			headers: { 'Content-Type': 'application/json' },
+			body: isBookScrape ? JSON.stringify({ url: body.url }) : undefined
+		});
+	} catch (e) {
+		log.error('scrape', 'scraper proxy network error', { endpoint, err: String(e) });
+		throw error(502, 'Could not reach scraper');
+	}
+
+	if (!res.ok && res.status >= 500) {
+		const text = await res.text().catch(() => '');
+		log.error('scrape', 'scraper returned error', { endpoint, status: res.status, body: text });
+	}
 
 	const data = await res.json().catch(() => ({}));