chore: migrate to v3, Doppler secrets, clean up legacy code

- Remove all pre-v3 code: scraper, ui-v2, backend v1, ios v1+v2, legacy CI workflows
- Flatten v3/ contents to repo root
- Add Doppler secrets management (project=libnovel, config=prd)
- Add justfile with doppler run wrappers for all docker compose commands
- Strip hardcoded env fallbacks from docker-compose.yml
- Add minimal README.md
- Clean up .gitignore

ui/src/hooks.server.ts

@@ -1,8 +1,47 @@
 import type { Handle } from '@sveltejs/kit';
+import { handleErrorWithSentry } from '@sentry/sveltekit';
+import * as Sentry from '@sentry/sveltekit';
 import { randomBytes, createHmac } from 'node:crypto';
 import { env } from '$env/dynamic/private';
+import { env as pubEnv } from '$env/dynamic/public';
 import { log } from '$lib/server/logger';
 import { createUserSession, touchUserSession, isSessionRevoked } from '$lib/server/pocketbase';
+import { drain as drainPresignCache } from '$lib/server/presignCache';
+
+// ─── Sentry / GlitchTip server-side error tracking ────────────────────────────
+// No-op when PUBLIC_GLITCHTIP_DSN is unset (e.g. local dev).
+if (pubEnv.PUBLIC_GLITCHTIP_DSN) {
+	Sentry.init({
+		dsn: pubEnv.PUBLIC_GLITCHTIP_DSN,
+		tracesSampleRate: 0.1
+	});
+}
+
+export const handleError = handleErrorWithSentry();
+
+// ─── Graceful shutdown ────────────────────────────────────────────────────────
+//
+// When Docker/Kubernetes sends SIGTERM (or the user sends SIGINT), we:
+//  1. Set shuttingDown = true so new requests immediately receive 503.
+//  2. Flush/drain in-process caches (presign URL cache).
+//  3. Allow Node.js to exit naturally once in-flight requests finish.
+//
+// adapter-node does not provide a built-in hook for this, so we wire it here
+// in hooks.server.ts which runs in the server Node.js process.
+
+let shuttingDown = false;
+
+function shutdown(signal: string) {
+	if (shuttingDown) return;
+	shuttingDown = true;
+	log.info('shutdown', `received ${signal}, draining in-flight requests`);
+	drainPresignCache();
+	// Don't call process.exit() — let Node exit naturally once the event loop
+	// is empty (adapter-node closes the HTTP server on its own).
+}
+
+process.once('SIGTERM', () => shutdown('SIGTERM'));
+process.once('SIGINT', () => shutdown('SIGINT'));
 
 const SESSION_COOKIE = 'libnovel_session';
 const AUTH_COOKIE = 'libnovel_auth';
@@ -70,6 +109,12 @@ export function parseAuthToken(token: string): { id: string; username: string; r
 // ─── Hook ─────────────────────────────────────────────────────────────────────
 
 export const handle: Handle = async ({ event, resolve }) => {
+	// During graceful shutdown, reject new requests immediately so the load
+	// balancer / Docker health-check can drain existing connections.
+	if (shuttingDown) {
+		return new Response('Service shutting down', { status: 503 });
+	}
+
 	// Anonymous session cookie (for reading progress)
 	let sessionId = event.cookies.get(SESSION_COOKIE) ?? '';
 	if (!sessionId) {