fix: configure postgres idle timeout and connection recycling for Railway

Railway proxy closes idle DB connections after ~60s, causing
CONNECTION_CLOSED errors on stale sockets. Set idle_timeout=20s and
max_lifetime=5m so postgres-js recycles connections before they die.

Also fix sendCommand to fall back to persistent device ID on reconnect.

server/src/db.ts

@@ -3,5 +3,9 @@ import postgres from "postgres";
 import { env } from "./env.js";
 import * as schema from "./schema.js";
 
-const client = postgres(env.DATABASE_URL);
+const client = postgres(env.DATABASE_URL, {
+  idle_timeout: 20,        // close idle connections after 20s (Railway proxy kills at ~60s)
+  max_lifetime: 60 * 5,    // recycle connections every 5 minutes
+  connect_timeout: 10,     // fail fast on connection issues
+});
 export const db = drizzle(client, { schema });

server/src/ws/sessions.ts

@@ -122,7 +122,8 @@ class SessionManager {
     command: Record<string, unknown>,
     timeout = DEFAULT_COMMAND_TIMEOUT
   ): Promise<unknown> {
-    const device = this.devices.get(deviceId);
+    // Try ephemeral ID first, then fall back to persistent DB ID (handles reconnects)
+    const device = this.devices.get(deviceId) ?? this.getDeviceByPersistentId(deviceId);
     if (!device) {
       return Promise.reject(new Error(`Device ${deviceId} not connected`));
     }