feat(app): wire up Express app factory and production entry point (Task 13)

Initializes DB, creates default admin user, connects brokers/PG sources,
starts query timers, and serves frontend/dist as SPA.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

display/middleware/src/api/index.ts

@@ -0,0 +1,45 @@
+import express from 'express';
+import cors from 'cors';
+import path from 'path';
+import authRouter from './routes/auth';
+import displayApiRouter from './routes/display-api';
+import mqttBrokersRouter from './routes/mqtt-brokers';
+import mqttTopicsRouter from './routes/mqtt-topics';
+import pgSourcesRouter from './routes/pg-sources';
+import datapointsRouter from './routes/datapoints';
+import displaysRouter from './routes/displays';
+import layoutsRouter from './routes/layouts';
+import { authMiddleware } from './middleware/auth';
+
+export function createApp(): express.Application {
+  const app = express();
+
+  app.use(cors());
+  app.use(express.json());
+
+  // Health check
+  app.get('/health', (_req, res) => {
+    res.json({ status: 'ok', timestamp: new Date().toISOString() });
+  });
+
+  // Public routes
+  app.use('/api/auth', authRouter);
+  app.use('/api/display', displayApiRouter);
+
+  // Protected management routes
+  app.use('/api/mqtt/brokers/:brokerId/topics', authMiddleware, mqttTopicsRouter);
+  app.use('/api/mqtt/brokers', authMiddleware, mqttBrokersRouter);
+  app.use('/api/pg/sources', authMiddleware, pgSourcesRouter);
+  app.use('/api/datapoints', authMiddleware, datapointsRouter);
+  app.use('/api/displays', authMiddleware, displaysRouter);
+  app.use('/api/layouts', authMiddleware, layoutsRouter);
+
+  // Serve frontend/dist as static files with SPA fallback
+  const frontendDist = path.join(__dirname, '..', '..', '..', 'frontend', 'dist');
+  app.use(express.static(frontendDist));
+  app.get('*', (_req, res) => {
+    res.sendFile(path.join(frontendDist, 'index.html'));
+  });
+
+  return app;
+}

display/middleware/src/index.ts

@@ -1,23 +1,54 @@
-import express from 'express';
-import cors from 'cors';
-import authRouter from './api/routes/auth';
+import bcrypt from 'bcryptjs';
+import { initDb } from './db/index';
+import { createApp } from './api/index';
+import { connectAllEnabledBrokers } from './modules/mqtt/broker-manager';
+import { connectAllEnabledSources } from './modules/postgres/source-manager';
+import { startAllQueryTimers } from './modules/postgres/query-scheduler';
 
-const app = express();
 const PORT = process.env.PORT ? parseInt(process.env.PORT) : 4000;
+const DB_PATH = process.env.DB_PATH ?? './display.db';
 
-app.use(cors());
-app.use(express.json());
+async function main(): Promise<void> {
+  // Initialize database
+  const db = initDb(DB_PATH);
 
-app.get('/health', (_req, res) => {
-  res.json({ status: 'ok', timestamp: new Date().toISOString() });
-});
+  // Create default admin user if no users exist
+  const userCount = db
+    .prepare('SELECT COUNT(*) as count FROM users')
+    .get() as { count: number };
 
-app.use('/api/auth', authRouter);
+  if (userCount.count === 0) {
+    const hash = bcrypt.hashSync('admin', 10);
+    db.run(
+      `INSERT INTO users (username, password_hash) VALUES (?, ?)`,
+      ['admin', hash]
+    );
+    console.log('Created default admin user (admin/admin)');
+  }
+
+  // Connect all enabled MQTT brokers
+  await connectAllEnabledBrokers();
+
+  // Connect all enabled PostgreSQL sources and start query timers
+  await connectAllEnabledSources();
+  startAllQueryTimers();
+
+  // Create and start Express app
+  const app = createApp();
 
-if (require.main === module) {
   app.listen(PORT, () => {
     console.log(`Middleware server running on port ${PORT}`);
   });
 }
 
-export default app;
+// Only run when executed directly (not during tests)
+if (require.main === module) {
+  main().catch((err) => {
+    console.error('Fatal startup error:', err);
+    process.exit(1);
+  });
+}
+
+// Export createApp for tests that import from index
+export { createApp };
+export default createApp();