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/books/+page.server.ts

@@ -1,11 +1,21 @@
 import type { PageServerLoad } from './$types';
 import { listBooks, allProgress } from '$lib/server/pocketbase';
+import { log } from '$lib/server/logger';
 
 export const load: PageServerLoad = async ({ locals }) => {
-	const [books, progressList] = await Promise.all([
-		listBooks(),
-		allProgress(locals.sessionId)
-	]);
+	let books: Awaited<ReturnType<typeof listBooks>>;
+	let progressList: Awaited<ReturnType<typeof allProgress>>;
+
+	try {
+		[books, progressList] = await Promise.all([
+			listBooks(),
+			allProgress(locals.sessionId)
+		]);
+	} catch (e) {
+		log.error('books', 'failed to load books or progress', { err: String(e) });
+		books = [];
+		progressList = [];
+	}
 
 	// Build a quick lookup: slug → last chapter read
 	const progressMap: Record<string, number> = {};

ui/src/routes/books/[slug]/+page.server.ts

@@ -1,17 +1,28 @@
 import { error } from '@sveltejs/kit';
 import type { PageServerLoad } from './$types';
 import { getBook, listChapterIdx, getProgress } from '$lib/server/pocketbase';
+import { log } from '$lib/server/logger';
 
 export const load: PageServerLoad = async ({ params, locals }) => {
 	const { slug } = params;
 
-	const [book, chapters, progress] = await Promise.all([
-		getBook(slug),
-		listChapterIdx(slug),
-		getProgress(locals.sessionId, slug)
-	]);
+	let book: Awaited<ReturnType<typeof getBook>>;
+	let chapters: Awaited<ReturnType<typeof listChapterIdx>>;
+	let progress: Awaited<ReturnType<typeof getProgress>>;
+
+	try {
+		[book, chapters, progress] = await Promise.all([
+			getBook(slug),
+			listChapterIdx(slug),
+			getProgress(locals.sessionId, slug)
+		]);
+	} catch (e) {
+		log.error('books', 'failed to load book page', { slug, err: String(e) });
+		throw error(500, 'Failed to load book');
+	}
 
 	if (!book) {
+		log.warn('books', 'book not found', { slug });
 		error(404, `Book "${slug}" not found`);
 	}
 

ui/src/routes/books/[slug]/chapters/[n]/+page.server.ts

@@ -3,6 +3,7 @@ import { marked } from 'marked';
 import type { PageServerLoad } from './$types';
 import { getBook, listChapterIdx } from '$lib/server/pocketbase';
 import { presignChapter } from '$lib/server/minio';
+import { log } from '$lib/server/logger';
 
 export const load: PageServerLoad = async ({ params, locals }) => {
 	const { slug } = params;
@@ -28,7 +29,7 @@ export const load: PageServerLoad = async ({ params, locals }) => {
 		html = await marked(markdown, { async: true });
 	} catch (e) {
 		// Don't hard-fail — show empty content with error message
-		console.error('Failed to fetch chapter content:', e);
+		log.error('chapter', 'failed to fetch chapter content', { slug, n, err: String(e) });
 	}
 
 	const prevChapter = chapters.find((c) => c.number === n - 1) ?? null;