add offline support

server.js

@@ -1,6 +1,7 @@
 import express from 'express';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
+import { offlineManifest } from './src/services/offline-manifest.js';
 import { config, ensureRuntimeDirectories } from './src/config.js';
 import { openDatabase } from './src/database.js';
 import { createApiRouter } from './src/routes/api.js';
@@ -18,6 +19,10 @@ app.use(express.json({
   type: ['application/json', 'application/*+json', 'text/json']
 }));
 app.use(express.urlencoded({ extended: true, limit: '2mb' }));
+app.get('/api/offline-manifest', (req, res) => {
+  res.setHeader('Cache-Control', 'no-store');
+  res.json(offlineManifest(publicDirectory));
+});
 app.use('/api', createApiRouter(db));
 app.use(express.static(publicDirectory, {
   extensions: ['html'],